# $ApsCVS: src/apsfilter/setup/devices-6.50,v 1.1 2000/12/16 12:33:07 andreas Exp $
#
                     Details of Ghostscript output devices                     

Table of contents

      + Notes on measurements
      + MS Windows printers
      + File formats
           
          o JPEG file format (JFIF)
          o TIFF file formats
       
      + H-P 8xx, 1100, and 1600 color inkjet printers
           
          o Drivers contained in gdevcd8.c
          o Further documentation
       
      + H-P 812, 815, 832, 880, 882, 895, and 970 color inkjet printers
           
          o Drivers contained in gdevcd8.c
          o Further documentation
       
      + Other H-P color inkjet printers
           
          o Drivers contained in gdevcdj.c
          o Default paper size
          o Deskjet physical limits
          o Printer properties (command-line parameters)
               
              # Bits per pixel
              # Deskjet properties
              # Paintjet XL300 / Paintjet XL properties
           
          o Gamma correction
          o HP's resolution-enhanced mode for Inkjet printers
          o General tips
       
      + Canon BJC-8200 printer
      + Other Canon BubbleJet (BJC) printers
           
          o History
          o Configuring and building the BJC drivers
               
              # Modify values in gdevbjc.h
              # CMYK-to-RGB color conversion
              # Vertical centering of the printable area
              # Page margins
              # Makefile and compilation
           
          o Use of the drivers
               
              # Supported Options and Defaults
              # Device information
              # Hardware margins
              # PostScript printer description (PPD) files
              # Customizing the PPD files
           
          o How to report problems
          o Acknowledgements
       
      + Epson Stylus color printer (see also uniprint)
           
          o Usage
          o Options
          o Application note and FAQ
               
              # Support for A3 paper
              # Margins, PageSize
              # Stylus Color II / IIs and 1500
           
          o Recommendations
               
              # Color dithering experiments with gdevstc 1.21
           
          o Color transformation
          o ColorAdjustMatrix
          o RGB / CMYK coding and transfer, and BitsPerPixel
          o What is weaving?
          o Print mode parameters
               
              # Unidirectional
              # Microweave, noWeave and OutputCode=deltarow
              # Model
           
          o Bugs and pitfalls
          o Tests
               
              # The various OutputCodes
              # Printing time related to other options
           
          o Acknowledgments
       
      + uniprint, a flexible unified printer driver
           
          o The state of this driver
          o Notes on uniprint's background
          o Godzilla's guide to the creation of Unified Printer Parameter (.upp
            ) files
          o All parameters in brief
          o uniprint's Roll of Honor
       
      + Sun SPARCprinter
           
          o Installation
          o Problems
       
      + Apple dot matrix printer
   
For other information, see the Ghostscript overview. You may also be interested
in how to build Ghostscript and install it, as well as the description of the 
driver interface.
-------------------------------------------------------------------------------

Notes on measurements

Several different important kinds of measures appear throughout this document:
inches, centimeters and millimeters, points, and bits per pixel.

Inches
    1 inch equals 2.54 centimeters. The inch measure is sometimes represented
    by "in" or a quotation mark (") to the right of a measure, like 8.5in or 
    8.5"". Dots per inch, "dpi", are the common measure of printing resolution
    for dot-matrix, laser, and ink-jet printers. U.S. "letter" paper is exactly
    8.5in×11in, approximately 21.6cm×27.9cm. (See in the usage documentation
    all the paper sizes predefined in Ghostscript.)
Centimeters and millimeters
    ISO standard paper sizes such as A4 and A3 are commonly represented in the
    SI units of centimeters and millimeters. Centimeters are abbreviated "cm",
    millimeters "mm". ISO A4 paper is quite close to 21.0×29.7 centimeters
    (approximately 8.3×11.7 inches).
Points
    Points are a measure traditionally used in the printing trade and now in
    PostScript, which specifies exactly 72 points per inch (approximately 28.35
    per centimeter). The paper sizes known to Ghostscript are defined in the
    initialization file gs_statd.ps in terms of points.
Bits per pixel
    Commonly abbreviated "bpp".

-------------------------------------------------------------------------------
MS Windows printers

This section was written by Russell Lang, the author of Ghostscript's
MS Windows-specific printer driver, and updated by Pierre Arnaud, the current
maintainer.

The mswinpr2 device uses MS Windows printer drivers, and thus should work with
any printer with device-independent bitmap (DIB) raster capabilities. The
printer resolution cannot be selected directly using PostScript commands from
Ghostscript: use the printer setup in the Control Panel instead. It is however
possible to specify a maximum resolution for the printed document (see below).

If no Windows printer name is specified in -sOutputFile, Ghostscript prompts
for a Windows printer using the standard Print Setup dialog box. You must set
the orientation to Portrait and the page size to that expected by Ghostscript;
otherwise the image will be clipped. Ghostscript sets the physical device size
to that of the Windows printer driver, but it does not update the PostScript
clipping path.

If a Windows printer name is specified in -sOutputFile using the format "\\
spool\printer_name", for instance
   
    gs ... -sOutputFile="\\spool\Apple LaserWriter II NT"

then Ghostscript attempts to open the Windows printer without prompting
(except, of course, if the printer is connected to FILE:). Ghostscript attempts
to set the Windows printer page size and orientation to match that expected by
Ghostscript, but doesn't always succeed. It uses this algorithm:
   
   
 1. If the requested page size matches one of the Windows standard page sizes +
    /- 2mm, request that standard size.
 2. Otherwise if the requested page size matches one of the Windows standard
    page sizes in landscape mode, ask for that standard size in landscape.
 3. Otherwise ask for the page size by specifying only its dimensions.
 4. Merge the requests above with the defaults. If the printer driver ignores
    the requested paper size, no error is generated: it will print on the wrong
    paper size.
 5. Open the Windows printer with the merged orientation and size.

The Ghostscript physical device size is updated to match the Windows printer
physical device.

Supported command-line parameters

The mswinpr2 device supports a limited number of command-line parameters (e.g.
it does not support setting the printer resolution). The recognized parameters
are the following:
   
    -sDEVICE=mswinpr2
        Selects the MS Windows printer device. If Ghostscript was not compiled
        with this device as the default output device, you have to specify it
        on the command line.
    -dNoCancel
        Hides the progress dialog, which shows the percent of the document page
        already processed and also provides a cancel button. This option is
        useful if GS is intended to print pages in the background, without any
        user intervention.
    -sOutputFile="\\spool\printer_name"
        Specifies which printer should be used. The printer_name should be
        typed exactly as it appears in the Printers control panel, including
        spaces.
   
   
Supported options (device properties)

Several extra options exist which cannot be set through the command-line, but
only by executing the appropriate PostScript setup code. These options can be
set through the inclusion of a setup file on the command-line:
   
    gs ... setup.ps ...

The setup.ps file is responsible for the device selection, therefore you should
not specify the -sDEVICE=mswinpr2 option on the command-line if you are using
such a setup file. Here is an example of such a setup file:
   
    mark
      /NoCancel      true                       % don't show the cancel dialog
      /BitsPerPixel  4                          % force 4 bits/pixel
      /UserSettings
        <<
          /DocumentName  (Ghostscript document) % name for the Windows spooler
          /MaxResolution 360                    % maximum document resolution
        >>
      (mswinpr2) finddevice                     % select the Windows device driver
      putdeviceprops
    setdevice
   
This example disables the progress dialog (same as the -dNoCancel option),
forces a 4 bits/pixel output resolution and specifies additional user settings,
such as the document name (which will be displayed by the Windows spooler for
the queued document) and the maximum resolution (here 360 dpi). It then finds
and selects an instance of the MS Windows device printer and activates it. This
will show the standard printer dialog, since no /OutputFile property was
specified.

The following options are available:
   
    /NoCancel boolean
        Disables (hides) the progress dialog when set to true or show the
        progress dialog if not set or set to false.
    /OutputFile string
        Specifies which printer should be used. The string should be of the
        form \\spool\printer_name, where the printer_name should be typed
        exactly as it appears in the Printers control panel, including spaces.
    /QueryUser integer
        Shows the standard printer dialog (1 or any other value), shows the 
        printer setup dialog (2) or selects the default Windows printer without
        any user interaction (3).
    /BitsPerPixel integer
        Sets the device depth to the specified bits per pixel. Currently
        supported values are 1 (monochrome), 4 (CMYK with screening handled by
        Ghostscript) and 24 (True Color, dithering handled by the Windows
        printer driver; this option can produce huge print jobs).
    /UserSettings dict
        Sets additional options, defined in a dictionary. The following
        properties can be set:
       
        /DocumentName string
            Defines the user friendly document name which will be displayed by
            the Windows spooler.
        /DocumentRange [n1 n2]
            Defines the range of pages contained in the document. This
            information can be used by the printer dialog, in conjunction with
            the following property.
        /SelectedRange [n1 n2]
            Defines the selected range of pages. This information will be
            displayed in the printer dialog and will be updated after the user
            interaction. A PostScript program could check these values and
            print only the selected page range.
        /MaxResolution dpi
            Specifies the maximum tolerated output resolution. If the selected
            printer has a higher resolution than dpi, then Ghostscript will
            render the document with a submultiple of the printer resolution.
            For example, if MaxResolution is set to 360 and the output printer
            supports up to 1200 dpi, then Ghostscript renders the document with
            an internal resolution of 1200/4=300 dpi. This can be very useful
            to reduce the memory requirements when printing in True Color on
            some high resolution ink-jet color printers.
       
       
   
   
These properties can be queried through the currentpagedevice operator. The
following PostScript code snippet shows how to do it for some of the
properties:
   
    currentpagedevice /BitsPerPixel get ==  % displays the selected depth
    
    currentpagedevice /UserSettings get     % get the additional options..
    /us exch def                            % ..and assign them to a variable
    
    us /DocumentName get ==     % displays the document name
    us /SelectedRange get ==    % displays the selected page range
    
    % other misc. informations (don't rely on them)
    
    us /Color get ==            % 1 => monochrome output, 2 => color output
    us /PrintCopies get ==      % displays the number of copies requested
   
There are a few undocumented informations stored in the UserSettings
dictionary. You should not rely on them. Their use is still experimental and
they could be removed in a future version.

Duplex printing

If the Windows printer supports the duplex printing feature, then it will also
be available through the mswinpr2 device. You can query for this support
through the /Duplex propery of the currentpagedevice. If it returns null, then
the feature is not supported by the selected printer. Otherwise, true means
that the printer is currently set up to print on both faces of the paper and 
false that it is not, but that it can.

The following example shows how to print on both faces of the paper (using the
long side of the paper as the reference):
   
    << /Duplex true /Tumble false >> setpagedevice
   
-------------------------------------------------------------------------------
File formats

JPEG file format (JFIF)

Ghostscript includes output drivers that can produce Independent JPEG Group
JFIF (JPEG File Interchange Format) files from PostScript images. Please note
that JPEG is a compression method specifically intended for continuous-tone
images such as photographs, not for graphics, and it is therefore quite
unsuitable for the vast majority of page images produced with PostScript, which
should be saved in a form better for graphics, such as Portable Network
Graphics (PNG) format. If you get crummy-looking JPEG files, don't blame
Ghostscript; instead consult a reference about uses and abuses of JPEG, such as
the JPEG FAQ
   
    http://www.faqs.org/faqs/jpeg-faq/

You can use the JPEG output drivers -- jpeg to produce color JPEG files and 
jpeggray for grayscale JPEGs -- the same as other file-format drivers: by
specifying the device name and an output file name, for example
   
    gs -sDEVICE=jpeg -sOutputFile=foo.jpg foo.ps

You can also use the -r switch to specify the imaging resolution and thus the
output file's size in pixels. The default resolution is normally 72×72dpi.

The JPEG devices support several special parameters to control the JPEG
"quality setting" (DCT quantization level).
   
    -dJPEGQ=N (integer from 0 to 100, default 75)
        Set the quality level N according to the widely used IJG quality scale,
        which balances the extent of compression against the fidelity of the
        image when reconstituted. Lower values drop more information from the
        image to achieve higher compression, and therefore have lower quality
        when reconstituted.
    -dQFactor=M (float from 0.0 to 1.0)
        Adobe's QFactor quality scale, which you may use in place of JPEGQ
        above. The QFactor scale is used by PostScript's DCTEncode filter but
        is nearly unheard-of elsewhere.
   
   
At this writing the default JPEG quality level of 75 is equivalent to -dQFactor
=0.5, but the JPEG default might change in the future. The JPEG drivers could
be extended to support additional JPEG compression options, such as the other
DCTEncode filter parameters, but so far they haven't been.

TIFF file formats

There are two unrelated sets of TIFF drivers: tiff12nc and tiff24nc, which
produce uncompressed color output, and all the other tiff* drivers, which
produce black-and-white output with different compression modes.

The black-and-white TIFF drivers support creation of files that are comprised
of more than a single strip. Multi-strip files reduce the memory requirement on
the reader, since readers need only store and process one strip at a time.
These drivers provide two parameters beyond the standard set:
   
    -dMaxStripSize=N (non-negative integer; default = 0)
        Set the maximum (uncompressed) size of a strip.
    -dAdjustWidth=true|false (Boolean; default = true)
        If true, then if the requested page width is close to either A4 (1728
        columns) or B4 (2048 columns), set the page width to A4 or B4
        respectively.
   
   
The TIFF 6.0 specification, Section 7, page 27, recommends that the size of
each strip be about 8 Kbytes. As an example, to generate the 'tiger' in tiffg4
format that has the recommended strip size, use:
   
    gs -sDEVICE=tiffg4 -sOutputFile=tiger.tif -dMaxStripSize=8192 examples/tiger.ps
   
If the value of the MaxStripSize parameter is smaller than a single image row,
then no error will be generated, and the TIFF file will be generated correctly
using one row per strip. Note that smaller strip sizes increase the size of the
file by increasing the size of the StripOffsets and StripByteCounts tables, and
by reducing the effectiveness of the compression which must start over for each
strip.

If the value of MaxStripSize is 0 (the default), then the entire image will be
a single strip.
-------------------------------------------------------------------------------

H-P 8xx, 1100, and 1600 color inkjet printers

This section, written by Uli Wortmann <uliw@erdw.ethz.ch>, deals with the
DeskJet 670, 690, 850, 855, 870, 890, 1100, and 1600.

Drivers contained in gdevcd8.c

The source module gdevcd8.c contains four generic drivers:
   
    cdj670         HP DeskJet 670 and 690            
    cdj850         HP DeskJet 850, 855, 870, and 1100
    cdj890         HP DeskJet 890                    
    cdj1600        HP DeskJet 1600                   
   
Further documentation

Credits: Much of the driver is based on ideas derived from the cdj550 driver of
George Cameron. The support for the hp670, hp690, hp890 and hp1600 was added by
Martin Gerbershagen.
   
    11.11.96     Version                                                       
                 1.0                                                           
    25.08.97     Version     Resolved all but one of the known bugs, introduced
                 1.2         a couple of perfomance improvements. Complete new 
                             color-transfer-function handling (see gamma).     
    01.06.98     Version     Due to the most welcome contribution of Martin    
                 1.3         Gerbershagen (ger@ulm.temic.de), support for the  
                             hp670, hp690 and hp890 and hp1600 has been added. 
                             Martin has also resolved all known bugs.          
                             Problems:Dark colors are still pale.              
   
The hp690 is supported through the hp670 device, the hp855, hp870 and the
hp1100 through the hp850 device. The driver needs no longer special switches to
be invoked except -sDEVICE=cdj850, -sDEVICE=CDJ890, -sDEVICE=CDJ670, or 
-sDevice=CDJ1600. The following switches are supported.
   
    -dPapertype=      0       plain paper [default]                            
                      1       bond paper                                       
                      2       special paper                                    
                      3       glossy film                                      
                      4       transparency film                                
                              Currently the lookup tables are unsuited for     
                              printing on special paper or transparencies. For 
                              these please revert to the gamma functions.      
    -dQuality=        -1      draft                                            
                      0       normal [default]                                 
                      1       presentation                                     
    -dRetStatus=      0       C-RET off                                        
                      1       C-RET on [default]                               
    -dMasterGamma     3.0     [default = 1.0]                                  
    =                                                                          
   
    Note: To take advantage of the calibrated color-transfer functions, be sure
    not to have any gamma statements left! If you need to (i.e., for overhead
    transparencies), you still can use the gamma functions, but they will
    override the built-in calibration. To use gamma in the traditional way, set
    MasterGamma to any value greater than 1.0 and less than 10.0. To adjust
    individual gamma values, you have to additionally set MasterGamma to a
    value greater than 1.0 and less than 10.0. With the next release, gamma
    functions will be dropped.

When using the driver, be aware that printing at 600dpi involves processing
large amounts of data (> 188MB !). Therefore the driver is not what you would
expect to be a fast driver ;-) This is no problem when printing a full-sized
color page (because printing itself is slow), but it's really annoying if you
print only text pages. Maybe I can optimize the code for text-only pages in a
later release. Right now, it is recommended to use the highest possible
optimisation level your compiler offers. For the time being, use the cdj550
device with -sBitsPerPixel=3 for fast proof prints. If you simply want to print
600dpi BW data, use the cdj550 device with -sBitsPerPixel=8 (or 1).

Since the printer itself is slow, it may help to set the process priority of
the gs process to "regular" or even less. On a 486/100MHz this is still
sufficient to maintain a continuous data flow. Note to OS/2 users: simply put
the gs window into the background or minimize it. Also make sure that 
print01.sys is invoked without the /irq switch (great speed improvement under
Warp4).

The printer default settings compensate for dot-gain by a calibrated
color-transfer function. If this appears to be too light for your business
graphs, or for overhead transparencies, feel free to set -dMasterGamma=1.7.
Furthermore, you may tweak the gamma values independently by setting 
-dGammaValC, -dGammaValM, -dGammaValY or -dGammaValK (if not set, the values
default to MasterGamma). This will only work when -dMasterGamma is set to a
value greater than 1.0.

Further information, bugs, tips etc, can be found at my website. To learn more
about gamma, see ftp://ftp.igd.fhg.de/pub/doc/colour/GammaFAQ.pdf.

Depending on how you transfer the files, under UNIX you may need to remove the
CRs of the CR-LF sequence used for end-of-line on DOS-based (MS Windows-based)
systems. You can do this in unpacking the files with unzip -a hp850.zip.

To compile with gs5.x or later, simply add to your makefile
   
    DEVICE_DEVS4=cdj850.dev cdj670.dev cdj890.dev cdj1600.dev

Have fun!

Uli <uliw@erdw.ethz.ch>
http://www.erdw.ethz.ch/~bonk/
-------------------------------------------------------------------------------

H-P 812, 815, 832, 880, 882, 895, and 970 color inkjet printers

This section, written by Matthew Gelhaus <mgelhaus@proaxis.com>, deals with the
DeskJet 812, 815, 832, 880, 882, 895, and 970.

This is a modified version of the HP8xx driver written by Uli Wortmann. More
information and download are available at http://www.proaxis.com/~mgelhaus/
linux/software/hp880c/hp880c.html.

Drivers contained in gdevcd8.c

The source module gdevcd8.c contains one generic driver:
   
    cdj880      HP DeskJet 812, 815, 832, 880, 882, 895, and 970 
   
Further documentation

Credits: This driver is based on the cdj850 driver by Uli Wortmann, and shares
the same internal structure, although the PCL3+ interpretation has changed.
   
    15.03.99     Version      Initial version, based on Version 1.3 of Uli     
                 1.3          Wortmann's driver.                               
    26.02.00     Version      Greatly improved color handling & dithering, but 
                 1.4beta      not yet complete enough to use for text.         
   
All printers are supported through the cdj880 device. Invoke with -sDEVICE=
cdj880. The following switches are supported.
   
    -dPapertype=      0       plain paper [default]                            
                      1       bond paper                                       
                      2       special paper                                    
                      3       glossy film                                      
                      4       transparency film                                
                              Currently the lookup tables are unsuited for     
                              printing on special paper or transparencies. For 
                              these please revert to the gamma functions.      
    -dQuality=        -1      draft                                            
                      0       normal [default]                                 
                      1       presentation                                     
    -dMasterGamma     3.0     [default = 1.0]                                  
    =                                                                          
   
The printer default settings compensate for dot-gain by a pre-defined
color-transfer function. If this appears to be too light for your business
graphs, or for overhead transparencies, feel free to set -dMasterGamma=1.7.
Furthermore, you may tweak the gamma values independently by setting 
-dGammaValC, -dGammaValM, -dGammaValY or -dGammaValK (if not set, the values
default to MasterGamma). This will only work when -dMasterGamma is set to a
value greater than 1.0.

Further information, bugs, tips etc, can be found at my website.

To compile with gs6.x or later, simply add to your makefile
   
    DEVICE_DEVS4=$(DD)cdj880.dev

Matthew Gelhaus <mgelhaus@proaxis.com>
http://www.proaxis.com/~mgelhaus
-------------------------------------------------------------------------------

H-P color inkjet printers

This section, written by George Cameron, deals with the DeskJet 500C, DeskJet
550C, PaintJet, PaintJet XL, PaintJet XL300, the DEC LJ250 operating in
PaintJet-compatible mode.

Drivers contained in gdevcdj.c

The source module gdevcdj.c contains six generic drivers:
   
    cdj500        HP DeskJet 500C and 540C                      
    cdj550        HP DeskJet 550C, 560C, 660C, 660Cse           
    pjxl300       HP PaintJet XL300, DeskJet 1200C, and CopyJet 
    pjtest        HP PaintJet                                   
    pjxltest      HP PaintJet XL                                
    declj250      DEC LJ250                                     
   
All 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 command line, for example
   
    gs -sDEVICE=cDeskJet -dBitsPerPixel=16 -dDepletion=1 -dShingling=2 tiger.ps

Note: the old names cDeskJet, cdjcolor and cdjmono drivers have been retained;
however, their functionality duplicates that available using the drivers above
(and cDeskJet is identical to cdj500). That is, 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 ISO A4;
otherwise it is U.S. letter size (see about paper sizes in the usage
documentation). You can specify other paper sizes on the command line,
including A3 for the PaintJet XL and PaintJet XL300, as also explained in the
usage documentation.

DeskJet physical limits

The DeskJet's maximum printing width is 2400 dots, or 8 inches (20.32cm). The
printer manuals say that the maximum recommended printing height on the page is
10.3 inches (26.16cm), 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 0.5 inches (1.27cm) of unprintable bottom margin, due to the
mechanical arrangement used to grab the paper. Side margins are approximately
0.25 inches (0.64cm) for U.S. letter paper, and 0.15 inches (0.38cm) for A4.

Printer properties (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, for
instance, like
   
    gs -dBitsPerPixel=32 -dShingling=1 ...

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

Bits per pixel

If the preprocessor symbol BITSPERPIXEL is defined as an integer (see below for
the range of allowable values), that number defines the default bits per pixel
(bit depth) for the generic drivers. If the symbol is undefined, the default is
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.

All of the drivers in gdevcdj.c accept a command line option to set the 
BitsPerPixel property. This gives considerable flexibility in choosing various
tradeoffs among speed, quality, colour, etc. The valid numbers are:
   
    1   A standard Ghostscript monochrome driver, using 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  A "cheaper" version of the 24-bit driver, which generates
        Floyd-Steinberg colour dithered output using the minimum memory (this
        may be helpful when using Ghostscript has not been compiled using a
        16-bit build environment). 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. It tends to produce rather larger raw
        data files, so they can also take longer to print.
    32  Only for the DeskJet 550C, which uses the black cartridge and the
        colour cartridge simultaneously (that is, CMYK printing). This printer
        can both be 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 small.)
   
   
DeskJet properties

    Name              Type                                                     
    ---------------------------------------------------------------------------
    BlackCorrect      int       Colour correction to give better blacks when   
                                using the DJ500C in colour mode. For example,  
                                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 and 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

    Name              Type                                                     
    ---------------------------------------------------------------------------
    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 the
                                maximum number of passes, giving slowest       
                                printing for highest quality                   
    RenderType        int       0   driver does dithering                      
                                1   snap to primaries                          
                                2   snap black to 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.         
                                                                               
   
    The PaintJet (non-XL) has 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-inch or 1/300-inch
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, such as
   
    gs ... gamma.ps colorpic.ps -c quit

where gamma.ps is
   
    %!
    /.fixtransfer {
      currentcolortransfer 4 {
        mark exch
        dup type dup /arraytype eq exch /packedarraytype eq or
        1 index xcheck and { /exec load } if
        0.333 /exp load
        ] cvx 4 1 roll
      } repeat setcolortransfer
    } bind odef
    .fixtransfer
    /setpagedevice { setpagedevice .fixtransfer } bind odef
   
This does the gamma correction after whatever correction the device might be
doing already. To do the correction before the current correction,
   
    %!
    /.fixtransfer {
      currentcolortransfer 4 {
        mark 0.333 /exp load 4 -1 roll
        dup type dup /arraytype eq exch /packedarraytype eq or
        1 index xcheck and { /exec load } if
        ] cvx 4 1 roll
      } repeat setcolortransfer
    } bind odef
    .fixtransfer
    /setpagedevice { setpagedevice .fixtransfer } bind odef
   
This example sets the gamma for R, G, and B to 3, which seems to work
reasonably well in practice.

HP's resolution-enhanced mode for Inkjet printers

This feature is available on HP's more recent inkjet printers, including the
DeskJet 520 (mono), 540 (mono or colour) and 560C (mono and colour). The colour
and monochrome drivers for the HP DeskJet 550c are (probably) the best you will
get for use with Ghostscript, for the following reasons.

These printers do not offer true 600×300dpi resolution. Those that print in
colour are strictly 300×300dpi in colour mode, while in mono mode there is a
pseudo 600×300dpi mode with the restriction that you can't print two adjacent
dots. In effect what you have is 600dpi dot positioning, but on average you
don't get more dots per line. This provides the possibility, for instance, to
have sharper character outlines, because you can place dots on the edges nearer
to their ideal positions. This is why it is worth doing.

However, HP will not support user-level programming of this resolution-enhanced
mode, one reason being that (I understand) all the dot spacing has to be done
by the driver, and if you get it wrong, you can actually damage the print head.

To summarise, you may lose a smidgin of (potential) text clarity using the 550c
drivers (cdj550, cdjcolor, cdjmono etc.), but other than that, they are the
ones for the job.

General tips

For all the printers above, the choice of paper is critically important to the
final results. The printer manuals suggest type of paper, but in general,
smoother, less fibrous types give better results. In particular, the special
ink-jet paper can make a big difference: 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 procedure 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 to
test drivers for the additional machines and report their findings back to me.
-------------------------------------------------------------------------------

Canon BJC-8200 printer

This section was contributed by the author of the uniprint configuration files
for the Canon BJC-8200, Stephan C. Buchert <scb@stelab.nagoya-u.ac.jp>. These
files also handle the Japanese Canon F850 printer.

Warning: Usage of this program is neither supported nor endorsed by the Canon
corporation. Please see the Ghostscript license regarding warranty.

Introduction

The Canon Bubble Jet printer BJC-8200 is designed for printing digital photos
and halftone images. Software drivers for Windows 95-2000 and Mac are usually
included and can be downloaded from the Canon web sites like http://
www.ccsi.canon.com/bjc/bjc8200/ for the US market. If these drivers cannot be
used for some reason, then at present Ghostscript is probably the alternative
giving the best results.

The BJC-8200 has features not found among the specs of earlier bubble jet
models (except the even more advanced BJC-8500) and is advertised to offer:
   
   
 1. microfine droplet technology;
 2. support for printing on a new type of paper, Photo Paper Pro;
 3. a printhead capable of printing up to 1200 DpI;
 4. individual ink tanks for 6 colors;
 5. an internal status monitor reporting low ink back to a driver;
 6. an optional color scanner cartridge for up to 600 DpI resolution.

Access to features 5 and 6 requires use of the original Canon drivers for the
foreseeable future. This README is about getting the printer features 1-3
working with Ghostscript. No (re)compilation of Ghostscript is normally
required.

Ghostscript comes with a relatively highly configurable driver, called uniprint
, for printers which understand raster images in various propriety formats.
Most options for this driver are usually organized into files having the suffix
".upp." Ghostscript versions >= 5.10 (or even earlier) include such uniprint
control files for the Canon BJC-610. They work also well for some other Canon
Bubble Jet models, for example for my BJC-35vII. But when using them for a
BJC-8200 the result is unsatisfactory.

The uniprint control files for the BJC-8200

After some experimenting with the options for uniprint I have obtained quite
satisfactory prints with my printer(*). This distribution includes six new
uniprint control files:
   
   
  * bj8pp12f.upp
  * bj8hg12f.upp
  * bj8gc12f.upp
  * bj8oh06n.upp
  * bj8ts06n.upp
  * bj8pa06n.upp

They are included in Ghostscript >=6.21. For older versions you can put them
anywhere in the Ghostscript search path (type "gs -h" to see the path), but
should perhaps add the files to the directory with the other *.upp files. This
is "/usr/share/ghostscript/gs6.01/lib" in my RedHat 6.1 Linux box with Aladdin
Ghostscript 6.01.

Here is an explanation of my file name convention: the prefix "bj8" should
perhaps be used for the Canon BJC-8200 and compatible (like the Japanese F850
and perhaps the non-Japanese BJC-8500) models. The next two letters indicate
the print media:
   
   
  * pp "Photo Paper Pro"
  * hg "High Gloss Photo Film"
  * gc "Glossy Photo Cards"
  * oh "OHP transparencies"
  * ts "T-shirt transfer"
  * pa "Plain Paper"

The numbers at positions 6 and 7 indicate the resolution
   
   
  * 12 1200x1200 DpIxDpI
  * 06 600x600 DpIxDpI

The last letter stands for a quality factor that effects also the print speed
(presumably related to the number of passes that the printhead makes).
   
   
  * f highest quality
  * n normal quality

Printing a postcard size (~10x15 cm^2) image at 1200x1200 DpI^2 takes about 3
minutes. The output of Ghostscript is then typically 4-5 MByte. The bootleneck
seems to be the transfer of the raster image in run-length encoded Canon format
to the printer (via the parallel port on my system) or the printer's speed, not
Ghostscript or the uniprint renderer.

Further Optimization for the Canon BJC-8200

So far I have only experimented with the printer initialization code at the
beginning of each page (-dupBeginPageCommand) and the resolution (-r). Other
options, particularly the transfer arrays (-dupBlackTransfer, -dupCyanTransfer,
-dupMagentaTransfer, -dupYellowTransfer) and the margins (-dupMargins) were
simply copied from the files for the BJC-610, but they may need to be changed
for optimized performance.

Here is information useful for changing or adding uniprint control files for
the BJC-8200:

In "-dupBeginPageCommand=..." use the line
   
    1b28 64 0400 04b0 04b0

for 1200x1200 resolution, and
   
    1b28 64 0400 0258 0258

for 600x600. The "-r" option in the control file must of course match this
line. Other resolutions might work as well, but I didn't try.

Crucial are the numbers in the lines like
   
       1b28 63 0300 3005 04
                       ^  ^
           Plain Paper 0  4 Highest quality
      OHP transparency 2  .
      T-shirt transfer 3  .
     Glossy Photo Film 5  .
      High Gloss Paper 6  0 Lowest quality
       Photo Paper Pro 9
   
Outlook

Presently uniprint can use the black (K), cyan (C), magenta (M), and yellow (Y)
colors in the BJC-8200. The unused colors are photo (or light) cyan (c) and
magenta (m). Also the Canon driver seems to use only CMYK, for example when
printing on Photo Paper Pro in "Camera" or "SuperPhoto" mode. These modes
supposedly produce prints of the best quality that the Canon driver can offer.
Other modes of Canon driver do use up to all six color cartridges (CMYKcm).
Therefore expanding uniprint's capabilities for six colors would be
interesting, but it may not increase the output quality of 6-color printers
such as the BJC-8200 drastically.

More control files for uniprint could be added in order to offer more
versatility for controlling the BJC-8200 within a Ghostscript installation. The
number of possible combinations for media type, resolution and print quality
factor is very large, many combinations would not make much sense, many might
be used here and there, but relatively rarely. The user would have to remember
a name for each combination that is used.

A better way would be to let the user patch optionally a user owned or system
wide uniprint control file before each print via some print tool. This is
similar to the approach taken by Canon with their driver for Windows. Similarly
a uniprint tool could also incorporate other functions such as printing test
and demo pages and the low ink warning once the protocol for this is known.
Clearly it would be difficult to code such a uniprint tool for all the
platforms where Ghostscript is running.

Usage on RedHat Linux

In order to install a BJC-8200 printer on a RedHat Linux system with RedHat's
printtool, you need also to insert with a text editor the contents of the file 
bj8.rpd into the RedHat printer database /usr/lib/rhs/rhs-printfilters/
printerdb. Insert it most appropriately after the section
   
    StartEntry: U_CanonBJC610
    .
    .
    .
    EndEntry
    
    < --- insert here "bj8.rpd" from this distribution:
    < --- StartEntry: U_CanonBJC8200
          .
          .
          .
   
Contacting the Author

E-mail address: <scb@stelab.nagoya-u.ac.jp>

Footnotes:

(*) Actually I have a F850, not a BJC-8200. That model is sold for the Japanese
market only. The specs and also the external look are the same as those of the
BJC-8200 models for the American and European markets. I expect that the raster
image mode which is used exclusively by Ghostscript is entirely compatible for
both models.

Stephan C. Buchert
-------------------------------------------------------------------------------

Other Canon BubbleJet (BJC) printers

This section was contributed by the author of the drivers, Yves Arrouye (<
yves.arrouye@usa.net>, but please do not send questions to him: he no longer
maintains these drivers.) The drivers handle Canon BJC-600, BJC-4xxx, BJC-70,
Stylewriter 2x00, and BJC-800 printers.

History

The BJC-600 driver was written in the first place by Yoshio Kuniyoshi and later
modified by Yves Arrouye. We tried to make it evolve synchronously, though
Yoshio cannot be reached since a long time ago. The drivers are based on code
for the HP printers by George Cameron (in fact, they are in the same file!), so
he's the first person to thank.

The 2.00 version of the drivers was a complete rewrite of the driver
(arguments, optimization, colour handling, in short: everything!) by Yves
Arrouye. That release was also the first one to be able to use the full width
of an A3 paper size. PostScript Printer Description (PPD) files for the drivers
were released with version 2.15. They are incomplete, but they can be used to
drive the printers' main features.

Configuring and building the BJC drivers

Modify values in gdevbjc.h

Configure the drivers by modifying the default values in the file gdevbjc.h or
on the compilation line. If you don't do that, the drivers use reasonable
defaults that make them work "as expected". All default values shown here are
defined in that file.

CMYK-to-RGB color conversion

By default, the drivers use the same algorithm as Ghostscript to convert CMYK
colors to RGB. If you prefer to use Adobe formulas, define USE_ADOBE_CMYK_RGB
when compiling. (See the top of the file gdevcdj.c to see the difference
between the two.)

Vertical centering of the printable area

The drivers center the imageable area horizontally but not vertically, so that
what can be printed does use the most of the output media. If you define 
BJC_DEFAULT_CENTEREDAREA when compiling, then the top and bottom margins will
be the same, resulting in a (smaller) vertically centered imageable area also.

Page margins

If you define USE_RECOMMENDED_MARGINS, then the top and bottom margins will be
the same (that is, BJC_DEFAULT_CENTEREDAREA will be defined for you) and the
margins will be the 12.4mm recommended by Canon. Since margins are complicated
(because one must rely on the mechanical precision of the printer), the drivers
do something about the bottom margin: by default the bottom margin is 9.54mm
for the BJC-600 driver and 7mm for the BJC-800. If you define USE_TIGHT_MARGINS
, then the bottom margin is 7mm for both drivers (but I never managed to get my
own BJC-600 to print a line on this low bound, hence the larger default).
Regardless of the presence of this definition, USE_FIXED_MARGINS will not allow
the BJC-800 to use the lower 7mm bottom margin, so if you have a problem with
the bottom margin on a BJC-800, just define that (without defining 
USE_TIGHT_MARGINS, of course).

A quick way to be sure the margins you selected is to print a file whose
contents are:
   
    %!
    clippath stroke showpage

If the margins are okay, you will get a rectangle visibly surrounding the
printable area. If they're not correct, one or more of the sides will be either
incomplete or completely unprinted.

Makefile and compilation

Make sure the bjc600 or bjc800 devices are in DEVICE_DEVS in the makefile; that
is, look in the makefile for your platform and add them if necessary -- they
may already be there. As of Ghostscript 5.10, for instance, one makefile has
   
    DEVICE_DEVS6=bj10e.dev bj200.dev bjc600.dev bjc800.dev

Use of the drivers

There are two drivers here. The "bjc600" one supports the BJC-600 and BJC-4xxx
(maybe the BJC-70 as well) and the "bjc800" one supports the BJC-800 series.
Remarks here that apply to both drivers use the name "bjc".

Supported Options and Defaults

Note: "options", "properties", and "parameters" designate the same thing:
device parameters that you can change.

Giving an option an incorrect value causes an error. Unless stated otherwise,
this error will be a rangecheckerror. Options may be set from the Ghostscript
command line (using the -d and -s switches or other predetermined switches if
they have an effect on the driver) or using the PostScript Level 2 
setpagedevice operator if Ghostscript has been compiled with the level2 or 
level3 device (which it should ;-)). There are no special-purpose operators
such as one was able to find in Level 1 printers.

The bjc uses 24 bits per pixel by default (unless you change the value of 
BJC_BITSPERPIXEL), corresponding to CMYK printing. Supported modes are 1 bpp
and 4 bpp (gray levels), 8 bpp, 16 bpp, 24 bpp and 32 bpp (colours). Colours
are preferably stored in the CMYK model (which means, for example, that with 16
bpp there are only 16 different shades of each color) but it is possible to
store them as RGB color for some depths. Some modes do Floyd-Steinberg
dithering and some don't, but use the default Ghostscript halftoning (in fact,
when halftoning is used, dithering takes also place but because of the low
point density it is usually not efficient, and thus invisible).
   
    ---------------------------------------------------------------------------
                 Descriptions of printing modes by bpp and Colors              
    ---------------------------------------------------------------------------
    bpp     Colors     Mode                                                    
    ---------------------------------------------------------------------------
    32        4        CMYK colour printing, Floyd-Steinberg dithering         
    24        4        The same. (But each primary colour is stored on 6 bits  
                       instead of 8.)                                          
    24        3        RGB colour printing, Floyd-Steinberg dithering. This    
                       mode does not use the black cartridge (that's why it    
                       exists, for when you don't want to use it ;-)). Each    
                       primary colour is stored in 8 bits as in the 32/4 mode, 
                       but black generation and under-color removal are done on
                       the driver side and not by Ghostscript, so you have no  
                       control over it. (This mode is no longer supported in   
                       this driver.)                                           
    16        4        CMYK colour printing, halftoned by Ghostscript. F-S     
                       dithering is still visible here (but the halftone       
                       patterns are visible too!).                             
    8         4        The same. (But each primary colour is stored in 2 bits  
                       instead of 4.)                                          
    8         3        RGB colour printing. This mode is not intended for use. 
                       What I mean is that it should be used only if you want  
                       to use custom halftone screens and the halftoning is    
                       broken using the 8/4 mode (some versions of Ghostscript 
                       have this problem).                                     
    8         1        Gray-level printing, Floyd-Steinberg dithering          
    1         1        Gray-level printing halftoned by Ghostscript            
   
These modes are selected using the BitsPerPixel and Colors integer options
(either from the command line or in a PostScript program using setpagedevice).
See below.

A note about darkness of what is printed: Canon printers do print dark, really.
And the Floyd-Steinberg dithering may eventually darken your image too. So you
may need to apply gamma correction by calling Ghostscript as in
   
    gs -sDEVICE=bjc600 gamma.ps myfile.ps

where gamma.ps changes the gamma correction (here to 3 for all colors); 0.45
gives me good results, but your mileage may vary. The bigger the value the
lighter the output:
   
    { 0.45 exp } dup dup currenttransfer setcolortransfer

The drivers support printing at 90dpi, 180dpi and 360dpi. Horizontal and
vertical resolutions must be the same or a limitcheck error will happen. A
rangecheck will happen too if the resolution is not 90 ×2^N. If the driver is
compiled with -DBJC_STRICT a rangecheck also happens if the resolution is not
one of those supported. This is not the case, as we expect that there may be a
720dpi bjc some day.

Here are the various options supported by the bjc drivers, along with their
types, supported values, effects, and usage:

BitsPerPixel (int)
    Choose the depth of the page. Valid values are 1, 8, 16, 24 (the default)
    and 32.
   
    Note that when this is set for the first time, the Colors property is
    automatically adjusted unless it is also specified. The table here shows
    the corresponding color models and the rendering method visible: "GS" for
    Ghostscript halftoning and "F-S" for Floyd-Steinberg dithering. When both
    are present it means that the dithering of halftones is visible. Default
    choices are indicated by asterisk "*".
        ---------------------------------------------------------
                         Valid Colors values for                 
                       allowed BitsPerPixel values               
        ---------------------------------------------------------
        bpp      Colors              Color model       Dithering 
        ---------------------------------------------------------
        32          4                CMYK              F-S       
        24          4         *      CMYK              F-S       
                    3                RGB               F-S       
        16          4                CMYK              GS, F-S   
        8           4         *      CMYK              GS        
                    3                RGB               GS        
                    1                K (CMYK)          F-S       
        1           1         *      K (CMYK)          GS        
       
   
    Also note that automagical change of one parameter depending on the other
    one does not work in a setpagedevice call. This means that if you want to
    change BitsPerPixel to a value whose valid Colors values do not include the
    actual Colors value, you must change Colors too.
   
Colors (int)
    Choose the number of color components from among 1, 3 and 4 (the default).
    This setting cannot be used in a PostScript program, only on Ghostscript's
    command line. See ProcessColorModel below for what to use to change the
    number of colors with PostScript code.
   
    Note that setting this property does limit the choices of BitsPerPixel. As
    for the previous property, its first setting may induce a setting of the
    "other value" (BitsPerPixel here). The table here indicates valid
    combinations with "V", default values with asterisk "*".
        -----------------------------------------------
                   Valid BitsPerPixel values           
                   for allowed Colors values           
        -----------------------------------------------
                               BitsPerPixel OK values  
                               ------------------------
         Colors      Type      32    24    16    8    1
        -----------------------------------------------
        4            CMYK      V     *     V     V     
        3            RGB             *           V     
        1            K                           V    *
       
   
    Also note that automagical change of one parameter depending on the other
    one does not work in a setpagedevice call. This means that if you want to
    change Colors to a value whose valid BitsPerPixel values don't include the
    actual BitsPerPixel value, you must change BitsPerPixel too.
   
ProcessColorModel (symbol)
    A symbol taken from /DeviceGray, /DeviceRGB or /DeviceCMYK which can be
    used to select 1, 3 or 4 colors respectively. Note that this parameter
    takes precedence over Colors, and that both affect the same variable of the
    driver. (See Colors above for values combined with BitsPerPixel.)

HWResolution (floats array)
    An array of two floats giving the horizontal and vertical resolution in
    dots per inch from among 90, 180 and 360 (the default). Both values must be
    the same. On the Ghostscript command line, the resolution may be changed
    with the -r switch.

ManualFeed (bool)
    Indicate that the sheets won't be fed automatically by the printer, false
    by default. (Not meaningful on the BJC-600, I fear.)

MediaType (string)
    The media to print on, chosen from among "PlainPaper", "CoatedPaper", "
    TransparencyFilm", "Envelope", "Card" and "Other". Default is "PlainPaper".
    For "Envelope", "Card" or "Other" the driver puts the printer into thick
    mode automatically regardless of the actual media weight.

MediaWeight (int or null)
    The weight of the media in grams per square meter. Null (the default)
    indicates that the weight is of no importance. If the specified media
    weight is greater than 105 (that is, the value of the compilation default 
    BJC???_MEDIAWEIGHT_THICKLIMIT) then the printer will be set to use thick
    paper.

PrintQuality (string)
    The quality of printing.
    Value     bjc600    bjc800                                                 
    ---------------------------------------------------------------------------
    Low                   X       Has the effect of making only two printing   
                                  passes instead of four, so should be twice   
                                  the speed; known as "CN" (Color Normal) mode 
    Draft       X         X       Unlights the "HQ" light on a BJC-600         
    Normal      X         X       Default for both drivers; lights the "HQ"    
                                  light on a BJC-600                           
    High        X         X       Means 200% black and 100% CMY; lights the    
                                  "Bk+" light on a BJC-600                     
   
DitheringType (string)
    Dithering algorithm from between "Floyd-Steinberg" and "None". "None" is
    the default for 1/1 print mode, "Floyd-Steinberg" for other modes. At the
    moment this parameter is read-only, though no error is generated if one
    tries to change it. This parameter is not of much value at the moment and
    is here mainly to reserve the name for future addition of dithering
    algorithms.

PrintColors (int)
    Mask for printing color. If 0, use black for any color; otherwise the value
    must be the sum of any of 1 (cyan), 2 (magenta), 4 (yellow) and 8 (black),
    indicating which colors will be used for printing. When printing colour,
    only colours specified will be printed (this means that some planes will be
    missing if a color's value above is omitted). When printing grays, black is
    used if it is present in the PrintColors; otherwise, the image is printed
    by superimposing each requested color.

MonochromePrint (bool)
    For bjc600 only, false by default. Substitute black for Cyan, Magenta and
    Yellow when printing -- useful, for example, to get some monochrome output
    of a dithered printing This is a hardware mechanism as opposed to the
    previous software one. I think that using this or setting PrintColors to 0
    will give the same results.

Note that the MediaType and ThickMedia options will be replaced by the use of
the device InputAttributes and OutputAttributes as soon as possible. Please
note too that the print mode may be reset at the start of printing, not at the
end. This is the expected behaviour. If you need to reset the printer to its
default state, simply print a file that does just a showpage.

Device information

Here is other information published by the driver that you will find in the 
deviceinfo dictionary.

OutputFaceUp (bool)
    This has the boolean value true, indicating that the sheets are stacked
    face up.

Version (float)
    In the form M.mmpp, where M is the major version, mm the bjc driver's minor
    version, and pp the specific driver minor version (that is, M.mm will
    always be the same for the bjc600 and bjc800 drivers).

VersionString (string)
    A string showing the driver version and other indications. At the moment,
    things like "a" or "b" may follow the version to indicate alpha or beta
    versions. The date of the last change to this version is given in the form
    MM/DD/YY (no, it won't adapt to your locale).

Hardware margins

The BJC printers have top and bottom hardware margins of 3mm and 7.1mm
respectively (Canon says 7mm, but this is unusable because of the rounding of
paper sizes to PostScript points). The left margin is 3.4mm for A4 and smaller
paper sizes, 6.4mm for U.S. paper sizes, envelopes and cards. It is 4.0mm for
A3 paper on the BJC-800.

The maximum printing width of a BJC-600 printer is 203mm. The maximum printing
width of a BJC-800 printer is 289mm on A3 paper, 203mm on U.S. letter and ISO
A4 paper.

PostScript printer description (PPD) files

The files CBJC600.PPD and CBJC800.PPD (whose long names are, respectively, 
Canon_BubbleJetColor_600.ppd and Canon_BubbleJetColor_800.ppd) are PPD files to
drive the features of the bjc600 and bjc800 drivers. They can be used, for
example, on NextStep systems (presumably on OpenStep systems too) and on Unix
systems with Adobe's TranScript and pslpr (not tested). The files are not
complete at the moment. Please note that NextStep's printing interface does not
correctly enforce constraints specified in these files (in UIConstraints
descriptions): you must force yourself to use valid combinations of options.

Customizing the PPD files

By default the PPD files are set for U.S. letter size paper, and they use a
normalized transfer function. If you choose to use A4 printing by default, you
must replace "Letter" with "A4" in these (noncontiguous) lines:
   
         [...]
    *DefaultPageSize: Letter
         [...]
    *DefaultRegion: Letter
         [...]
    *DefaultImageableArea: Letter
         [...]
   
Some versions of Ghostscript have problems with normalized colors, which makes
them add magenta in gray levels. If you experience this problem, in the PPD
file replace the line
   
    *DefaultTransfer: Normalized

with the alternate line
   
    *DefaultTransfer: Null

The "thick media" option is implemented by choosing a value of 120 or 80 (for
thick and thin media respectively) for the MediaWeight feature of the drivers.
If you ever change the threshold for thick media in the driver code, you may
need to change the values in the PPD files too.

All customization should be done using the "*Include:" feature of PPD files so
that your local changes will be retained if you update the PPD files.

How to report problems

Yves Arrouye no longer maintains this driver, and will not answer questions
about it. If you are posting a question about it in a public form, please be as
descriptive as possible, and please send information that can be used to
reproduce the problem. Don't forget to say which driver you use, and in what
version. Version information can be found in the source code of the driver or
by issuing the following command in a shell:
   
    echo "currentpagedevice /VersionString get ==" | gs -q -sDEVICE=bjc600 -

Acknowledgements

I am particularly grateful to Yoshio Kuniyoshi <yoshio@nak.math.keio.ac.jp>
without whom I'd never make these drivers, and also to L. Peter Deutsch, who
answered all my (often silly) questions about Ghostscript's driver interface.

Thanks also to the people who volunteered to beta-test the v2.x BJC drivers:
David Gaudine <david@donald.concordia.ca>, Robert M. Kenney <rmk@unh.edu>,
James McPherson <someone@erols.com> and Ian Thurlbeck <ian@stams.strath.ac.uk>
(listed alphabetically) were particularly helpful by discovering bugs and
helping find out exact paper margins on printers I don't have access to.

And many thanks to Klaus-Gunther Hess <ghess@elmos.de> for looking at the
dithering code and devising a good CMYK dithering algorithm for the Epson
Stylus Color, which I then adapted to the code of these drivers.
-------------------------------------------------------------------------------

Epson Stylus color printer (see also uniprint)

This section was contributed by Gunther Hess <ghess@elmos.de>, who also wrote 
uniprint, a later set of drivers. You should probably see the section on 
uniprint for whether it might be better for your uses than this driver.

Usage

This driver is selected with "-sDEVICE=stcolor", producing output for an Epson
Stylus Color at 360dpi resolution by default. But it can do much more with this
printer, and with significantly better quality, than with the default mode; and
it can also produce code for monochrome versions of the printer. This can be
achieved via either command-line options or Ghostscript input. For convenience
a PostScript file is supplied for use as an initial input file. Try the
following command:
   
    gs -sDEVICE=stcolor -r{Xdpi}x{Ydpi} stcolor.ps {YourFile.ps}

where {Xdpi} is one of 180, 360, or 720 and {Ydpi} is one of 90, 180, 360, or
720. The result should be significantly better. You may use stcolor.ps with
other devices too, but I do not recommend this, since it does nothing then. 
stcolor.ps should be available with binary distributions and should reside in
the same directory as other Ghostscript initialization files or in the same
directory as the files to be printed. Thus if Ghostscript is part of your
printer-spooler, you can insert
   
    (stcolor.ps) findlibfile { pop run } if pop

in files you want to use the improved algorithms. You may want to adapt 
stcolor.ps file to your specific needs. The methods and options for this are
described here, but this description is restricted to Ghostscript options,
while their manipulation at the PostScript level is documented in the material
on the relationship of Ghostscript and PostScript and in stcolor.ps.

Options

Now to explain the options (as written on my UNIX system). The order is somehow
related to their use during the printing process:

-dUnidirectional
    Force unidirectional printing, recommended for transparencies

-dMicroweave
    Enable the printer's "microweave" feature; see "What is weaving?" below.

-dnoWeave
    Disable any Weaving (overrides -dMicroweave)

-dSoftweave
    Enable the driver's internal weaving. Note that Softweave works only with
    the original Stylus Color and the PRO-Series.

-sDithering={name}
    Select another dithering algorithm (name) from among
        gscmyk      fast color output, CMYK process color model (default)      
        gsmono      fast monochrome output                                     
        gsrgb       fast color output, RGB process color model                 
        fsmono      Floyd-Steinberg, monochrome                                
        fsrgb       Floyd-Steinberg, RGB process color model (almost identical 
                    to the cdj550/bjc algorithm)                               
        fsx4        Floyd-Steinberg, CMYK process color model (shares code with
                    fsmono and fsrgb, but is algorithmically really bad)       
        fscmyk      Floyd-Steinberg, CMYK process color model and proper       
                    modifications for CMYK                                     
        hscmyk      modified Floyd-Steinberg with CMYK model ("hs" stands for  
                    "hess" not for "high speed", but the major difference from 
                    fscmyk is speed)                                           
        fs2         algorithm by Steven Singer (RGB) should be identical to    
                    escp2cfs2.                                                 
       
   
-dBitsPerPixel={1...32}
    number of bits used for pixel storage; the larger the value, the better the
    quality -- at least in theory. In fsrgb one can gain some speed by
    restricting to 24 bits rather than the default 30.

-dFlag0
    causes some algorithms to select a uniform initialisation rather than a set
    of random values. May yield a sharper image impression at the cost of
    dithering artifacts. (Applies to hscmyk and all fs modes, except for fs2,
    which always uses a constant initialization.)

-dFlag1 ... -dFlag4
    Available for future algorithms.

-dColorAdjustMatrix='{three, nine, or sixteen floating-point values}'
    This is a matrix to adjust the colors. Values should be between -1.0 and
    1.0, and the number of values depends on the color model the selected
    algorithm uses. In RGB and CMYK modes a matrix with 1.0 on the diagonal
    produces no transformation. This feature is really required, but I could
    not identify a similar feature at the language level, so I implemented it,
    but I don't know reasonable values yet.

-dCtransfer='{float float ...}' or
-dMtransfer=..., -dY..., -dK... or
-dRtransfer='{float float ...}' or
-dG..., -dB... or
-dKtransfer='{float float ...}'
    Which you use depends on the algorithm, which may be either either CMYK,
    RGB or monochrome. The values are arrays of floats in the range from 0 to
    1.0, representing the visible color intensity for the device. One may
    achieve similar effects with setcolortransfer at the language level, but
    this takes more time and the underlying code for the driver-specific
    parameters is still required. The size of the arrays is arbitrary and the
    defaults are "{0.0 1.0}", which is a linear characteristic. Most of the
    code in stcolor.ps are better transfer arrays.

-dKcoding='{float...}'
-dC..., -dM... etc.
    Arrays between 0.0 and 1.0, controlling the internal coding of the color
    values. Clever use of these arrays may yield further enhancements, but I
    have no experience yet. (To be discontinued with version 2.x.)

-sModel=st800
    Causes output to be suitable for the monochrome Stylus 800 (no weaving, no
    color).

-sOutputCode={name}
    Can be either "plain", "runlength" or "deltarow" and changes the ESC/P2
    coding technique used by the driver. The default is to use runlength
    encoding. "plain" selects uncompressed encoding and generates enormous
    amounts of data.

-descp_Band=1/8/15/24
    Number of nozzles of scanlines used in printing, Useful only with -dnoWeave
    . Larger Values yield smaller code, but this doesn't increase the printing
    speed.

-descp_Width=N
    Number of pixels Printed in each scan Line. (Useful only when tuning
    margins; see below)

-descp_Height=pixels
    Length of the entire page in pixels. (Parameter of "ESC(C" in default
    initialization.)

-descp_Top=scan lines
    Top margin in scan lines. (First parameter of "ESC(c" in default
    initialization.)

-descp_Bottom=scan lines
    Bottom margin in scan lines. (Second parameter of "ESC(c" in default
    initialization.)

-sescp_Init="string"
    Override for the initialization sequence. (Must set graphics mode 1 and
    units.)

-sescp_Release="string"
    Overrides the release sequence, "ESC @ FF" by default.

ESC/P2 allows any resolutions to be valid in theory, but only -r360x360 (the
default) and -r720x720 (not on STC-IIs ? and st800) are known to work with most
printers.

    ---------------------------------------------------------------------------
                             Valid option combinations                         
                            Stylus I & Pro-Series only                         
    ---------------------------------------------------------------------------
    Resolution       escp_Band      Weave usable              escp_Band &      
                                                              number of passes 
    ---------------------------------------------------------------------------
    180x90           15             noWeave                                    
    180x180          1 , 8, 24      noWeave, Microweave       15/2 SoftWeave   
    180x360                                                   15/4 SoftWeave   
    180x720                                                   15/8 SoftWeave   
    360x90           15             noWeave                                    
    360x180          1, 8, 24       noWeave, Microweave       15/2 SoftWeave   
    360x360          1, 8, 24       noWeave, Microweave       15/4 SoftWeave   
    360x720                                                   15/8 SoftWeave   
    720x90           15             noWeave                                    
    720x180                                                   15/2 SoftWeave   
    720x360                                                   15/4 SoftWeave   
    720x720          1              noWeave, Microweave       15/8 SoftWeave   
   
    Beware: there are only few validity checks for parameters. A good example
    is escp_Band: if you set this, the driver uses your value even if the value
    is not supported by the printer. You asked for it and you got it!

Application note and FAQ

Quite a bunch of parameters. Hopefully you never need any of them, besides
feeding stcolor.ps to Ghostscript in front of your input.

After answering some questions over fifty times I prepared a FAQ. Here is
version 1.3 of the FAQ, as of stcolor version 1.20 (for Ghostscript 3.50).

Support for A3 paper

Yes, this driver supports the A3-size printer: merely set the required pagesize
and margins. A simple way to do this is to specify the command-line switch "
-sPAPERSIZE=a3" or include the procedure call "a3" in the PostScript prolog
section. To optimize the printable area or set the proper margins, see the next
paragraph.

Margins, PageSize

I refuse to add code to stcolor that tries to guess the proper margins or page
size, because I found that such guessing is usually wrong and needs correction
in either the source or the parameters. You can modify stcolor.ps to do that,
however. After the line
   
    mark % prepare stack for "putdeviceprops"

insert these lines, which define page size and margins in points:
   
    /.HWMargins [9.0 39.96 12.6 9.0]     % Left, bottom, right, top (1/72")
    /PageSize   [597.6 842.4]            % Paper, including margins (1/72")
    /Margins [ % neg. Offset to Left/Top in Pixels
       4 index 0 get STCold /HWResolution get 0 get mul 72 div neg
       5 index 3 get STCold /HWResolution get 1 get mul 72 div neg
    ]
   
Feel free to change the values of .HWMargins and PageSize to match your needs;
the values given are the defaults when the driver is compiled with "-DA4". This
option or its omission may cause trouble: the Stylus Color can print up to
exactly 8 inches (2880 pixels) at 360dpi. The remaining paper is the margin,
where the left margin varies only slightly with the paper size, while the right
margin is significantly increased for wider paper, such as U.S. letter size.

Note that if you are using an ISO paper size with a version of stcolor after
1.20 and compiled without "-DA4", then the default margin is too large, and you
need to add the proper ".HWMargins" to the command line or to stcolor.ps.

Stylus Color II / IIs and 1500

First the good news: the driver can print on the Stylus Color II. Now the bad
news:
   
   
  * According to Epson support the driver "abuses" the color capabilities. (See
    "Future Plans" for details.)
  * You need some parameters on the command line (or in stcolor.ps).
  * I doubted that it would be usable with the Stylus Color IIs, but it is
    usable and suffers from mixing problems!

To make things work, you MUST disable the driver's internal weaving (Softweave
), in one of these two ways:
   
    gs -dMicroweave ...
    gs -dnoWeave -descp_Band=1 ...

Version 1.90, current as of Ghostscript 5.10, fixes this bug by new default
behaviour. I experienced significantly increased printing speed with the second
variant on the old Stylus Color, when printing mostly monochrome data.

Recommendations

The next section is a contribution from Jason Patterson <
jason@reflections.com.au> who evaluated a previous version (1.17). Ghostscript
was invoked as follows:
   
    gs  -sDEVICE=stcolor -r720x720 -sDithering=... -sOutputFile=escp.out
        stcolor.ps whatsoever.ps
   
   
where "..." is the name of the desired algorithm. stcolor.ps was omitted for
the gs-algorithms (gsmono, gsrgb and gscmyk), for which it is useless and would
not allow the selection of "gscmyk".

Color dithering experiments with gdevstc 1.21

Here are data about the EPSON Stylus Color driver's different dithering
methods, based on a little experiment using four good quality scanned images of
quite varied nature, to begin with, a summary of the results of the four
experiments. Sanity note: the results here are from only four images and a
total of 24 printouts (eight on 720dpi paper, sixteen on plain paper). Your
results will almost certainly vary, and your standards might not be the same as
mine, so use these results only as a guide, not as a formal evaluation.
   
    ---------------------------------------------------------------------------
                            Quality of output by method                        
    ---------------------------------------------------------------------------
                                                                               
    ---------------------------------------------------------------------------
    gsmono      Pretty much what you'd expect from a mono ordered pattern.     
                Looks like what a lot of mono laser printers produce.          
    fsmono      Excellent for monochrome.                                      
    gscmyk      Not very good, but expected from an ordered pattern.           
    gsrgb       A little better than gscmyk. More consistent looking.          
    fs2         Good, but not quite as good as fsrgb. Gets the brightness      
                wrong: too light at 720dpi, too dark at 360dpi.                
    fsrgb       Very good, but a little too dark and has a slight blue tint.   
    hscmyk      Excellent. Slightly better than fsrgb and fs2. Better than     
                fscmyk on some images, almost the same on most.                
    fscmyk      Best. Very, very slightly better than hscmyk. On some images   
                nearly as good as the EPSON demos done with the MS Windows     
                driver.                                                        
   
    --------------------------------------------
    Overall visual quality (1-10), best to worst
    --------------------------------------------
    Monochrome                                  
           fsmono       ******************      
           gsmono       **********              
                        0 1 2 3 4 5 6 7 8 9 10  
    --------------------------------------------
    Colour                                      
           fscmyk       *******************     
           hscmyk       *******************     
           fsrgb        ******************      
           fs2          *****************       
           gsrgb        **********              
           gscmyk       *********               
                        0 1 2 3 4 5 6 7 8 9 10  
   
Color transformation

In the initial version of the driver distributed with Ghostscript 3.33, the
parameter "SpotSize" was the only way to manipulate the colors at the driver
level. According to the parameters enumerated above, this has changed
significantly with version 1.16 and above as a result an ongoing discussion
about dithering algorithms and "false color" on the Epson Stylus Color. This
initiated the transformation of the stcolor driver into a framework for
different dithering algorithms, providing a generalized interface to the
internal Ghostscript color models and the other data structures related to
Ghostscript drivers.

The main thing such a framework should be able to do is to deliver the values
the dithering algorithm needs; and since this directly influences the optical
image impression, this transformation should be adjustable without the need for
recompilation and relinking. In general the process can be described as
follows:
   
    ColorAdjustMatrix    Coding                     Transfer                   
    |   Ghostscript    |   =>   |   Ghostscript   |    =>    | Dithering data |
           color                      raster                                   
    |                  |        |   1/2/4/8/16/   |          |                |
                                      32-bit                                   
    |   1/3/4 16-bit   |        |  1/3/4 values   |          |   (arbitrary   |
           values                                                  type)       
   
Due to the limitations on raster storage, information is lost in the first
transformation step, except for the 16-bit monochrome mode. So any color
adjustment should take place before this step and this is where the optional 
ColorAdjustMatrix works.

The first transformation step, called "coding", is controlled by the ?coding
arrays. The decoding process expands the range of values expontentially to a
larger range than that provided by the initial Ghostscript color model, and is
therefore a reasonable place to make device- or algorithm-specific adjustments.
This is where the ?transfer arrays are used. Array access might be not the
fastest method, but its generality is superior, so this step is always based
upon internally algorithm-specific array access. If 8 bits are stored per color
component and if the algorithm uses bytes too, the second transformation is
included within the first, which saves significant computation time when
printing the data.

ColorAdjustMatrix

The driver supports different values for ProcessColorModel, which raises the
need for different color adjustments. Here "CAM" stands for "ColorAdjustMatrix
".

DeviceGray (three floats)
    if ((r == g) && (g == b))
       K' = 1.0 - R;
    else
       K' = 1.0 - CAM[0] * R + CAM[1] * G + CAM[2] * B;
   
    According to the documentation on drivers, the latter (the "else" clause)
    should never happen.
   
DeviceRGB (nine floats)
    if((r == g) && (g == b))
       R' = B' = G' = R;
    else
       R' = CAM[0]*R + CAM[1]*G + CAM[2]*B;
       G' = CAM[3]*R + CAM[4]*G + CAM[5]*B;
       B' = CAM[6]*R + CAM[7]*G + CAM[8]*B;
   
    The printer always uses four inks, so a special treatment of black is
    provided. Algorithms may take special action if R, G, and B are all equal.
   
DeviceCMYK (sixteen floats)
    if((c == m) && (m == y))
       K' = max(C,K);
       C' = M' = Y' = 0;
    else
       K  = min(C,M,Y);
       if((K > 0) && ColorAdjustMatrix_present) { => UCR
          C -= K;
          M -= K;
          Y -= K;
       }
    
       C' = CAM[ 0]*C + CAM[ 1]*M + CAM[ 2]*Y + CAM[ 3]*K;
       M' = CAM[ 4]*C + CAM[ 5]*M + CAM[ 6]*Y + CAM[ 7]*K;
       Y' = CAM[ 8]*C + CAM[ 9]*M + CAM[10]*Y + CAM[11]*K;
       K' = CAM[12]*C + CAM[13]*M + CAM[14]*Y + CAM[15]*K;
   
    Again we have a special black treatment. "max(C,K)" was introduced because
    of a slight misbehaviour of Ghostscript, which delivers black under certain
    circumstances as (1,1,1,0). Normally, when no special black separation and
    undercolor removal procedures are defined at the PostScript level, either
    (C,M,Y,0) or (0,0,0,K) values are mapped. This would make the extended 
    ColorAdjustMatrix quite tedious, and so during mapping, black separation is
    done for (C,M,Y,0) requests; and if there is a ColorAdjustMatrix,
    undercolor removal is used too. In other words the default matrix is:
        1 0 0 1
        0 1 0 1
        0 0 1 1
        0 0 0 1
       
   
    and it is applied to CMYK values with separated and removed black. Raising
    the CMY coefficients while lowering the K coefficients reduces black and
    intensifies color. But be careful, because even small deviations from the
    default cause drastic changes.
   
If no ColorAdjustMatrix is set, the matrix computations are skipped. Thus the
transformation reduces to range inversion in monochrome mode and black
separation in CMYK mode.

RGB / CMYK coding and transfer, and BitsPerPixel

These two (groups of) parameters are arrays of floating-point numbers in the
range 0.0 to 1.0. They control the truncation to the desired number of bits
stored in raster memory (BitsPerPixel) and the ink density. The "truncation"
may become a nonlinear function if any of the ?coding arrays is set. Assume the
following Ghostscript invocation:
   
    gs -sDEVICE=stcolor -sDithering=fscmyk -dBitsPerPixel=16 \
         -dKcoding='{ 0.0 0.09 0.9 1.0 }' \
         -dMcoding='{ 0.0 0.09 0.9 1.0 }' \
       -dKtransfer='{ 0.0 0.09 0.9 1.0 }' \
       -dYtransfer='{ 0.0 0.09 0.9 1.0 }'
   
We may have either or both of ?coding and ?transfer, giving four possible
combinations. (These four combinations appear in the given example.) The
resulting mapping appears in the following tables, where except for the
internal Indices (4 components × 4 bits = 16 BitsPerPixel), all values are
normalized to the range 0 to 1. The actual range is 0 to 65535 for the
Ghostscript color and 0 to 16777215 for the ink values delivered to the fscmyk
algorithm. Sorry for the bunch of numbers following, but you may try this
example in conjunction with stcinfo.ps, which should give you a graphical
printout of the following numbers when you issue a showpage command.
   
                        Cyan                           Magenta           
            -----------------------------   -----------------------------
    CI/15   gs_color_values    CI    Ink    gs_color_values    CI    Ink 
    ---------------------------------------------------------------------
    0.000    0.000 - 0.062      0   0.000    -0.123 - 0.123     0   0.000
    0.067    0.063 - 0.125      1   0.067    0.123 - 0.299      1   0.247
    0.133    0.125 - 0.187      2   0.133    0.299 - 0.365      2   0.351
    0.200    0.188 - 0.250      3   0.200    0.365 - 0.392      3   0.379
    0.267    0.250 - 0.312      4   0.267    0.392 - 0.420      4   0.406
    0.333    0.313 - 0.375      5   0.333    0.420 - 0.447      5   0.433
    0.400    0.375 - 0.437      6   0.400    0.447 - 0.475      6   0.461
    0.467    0.438 - 0.500      7   0.467    0.475 - 0.502      7   0.488
    0.533    0.500 - 0.562      8   0.533    0.502 - 0.529      8   0.516
    0.600    0.563 - 0.625      9   0.600    0.529 - 0.557      9   0.543
    0.667    0.625 - 0.687     10   0.667    0.557 - 0.584     10   0.571
    0.733    0.688 - 0.750     11   0.733    0.584 - 0.612     11   0.598
    0.800    0.750 - 0.812     12   0.800    0.612 - 0.639     12   0.626
    0.867    0.813 - 0.875     13   0.867    0.639 - 0.715     13   0.653
    0.933    0.875 - 0.937     14   0.933    0.715 - 0.889     14   0.778
    1.000    0.938 - 1.000     15   1.000    0.889 - 1.111     15   1.000
   
The difference between cyan and magenta is the presence of a coding array. The
coding process must map a range of color values to each of the sixteen
component indices. If no coding array is given, this is accomplished by
dividing by 4096, equivalent to a right shift by 12 bits. The final ink density
resides in the given interval and moves from the left to the right side from 0
to 15. For magenta there is a coding array and the ink value matches the center
of the intervals. But the distribution of the mapped intervals follows the
given coding array and is nonlinear in the linear color space of Ghostscript.

Now let us take a look at the case with transfer arrays:
   
                       Yellow                           Black            
            -----------------------------   -----------------------------
    CI/15   gs_color_values    CI    Ink    gs_color_values    CI    Ink 
    ---------------------------------------------------------------------
    0.000    0.000 - 0.062      0   0.000    -0.123 - 0.123     0   0.000
    0.067    0.063 - 0.125      1   0.018    0.123 - 0.299      1   0.067
    0.133    0.125 - 0.187      2   0.036    0.299 - 0.365      2   0.133
    0.200    0.188 - 0.250      3   0.054    0.365 - 0.392      3   0.200
    0.267    0.250 - 0.312      4   0.072    0.392 - 0.420      4   0.267
    0.333    0.313 - 0.375      5   0.090    0.420 - 0.447      5   0.333
    0.400    0.375 - 0.437      6   0.252    0.447 - 0.475      6   0.400
    0.467    0.438 - 0.500      7   0.414    0.475 - 0.502      7   0.467
    0.533    0.500 - 0.562      8   0.576    0.502 - 0.529      8   0.533
    0.600    0.563 - 0.625      9   0.738    0.529 - 0.557      9   0.600
    0.667    0.625 - 0.687     10   0.900    0.557 - 0.584     10   0.667
    0.733    0.688 - 0.750     11   0.920    0.584 - 0.612     11   0.733
    0.800    0.750 - 0.812     12   0.940    0.612 - 0.639     12   0.800
    0.867    0.813 - 0.875     13   0.960    0.639 - 0.715     13   0.867
    0.933    0.875 - 0.937     14   0.980    0.715 - 0.889     14   0.933
    1.000    0.938 - 1.000     15   1.000    0.889 - 1.111     15   1.000
   
Yellow uses a transfer array. There is no linear correspondence between the
color and the ink values: this correspondence is defined through the given
array. In other words, the transfer arrays define a nonlinear ink
characteristic, which is exactly the same functionality that PostScript's "
(color)transfer" function provides.

While for yellow the intervals match the intervals used with cyan, for black
the intervals match the magenta intervals. But watch the correspondence between
the CI/15 values and the ink density for black: this is a linear distribution
in the ink domain.

Not a bad idea, I think. Consider the fs2 algorithm: it uses values in the
range 0 to 255. If any transfer array were alone, some of the 256 possible
values would never be used and others would be used for adjacent intervals
several times. Establishing an identical coding array solves this problem, so
the full potential of the algorithm is used.

Another useful feature of the coding arrays is that they are internally
normalized to the range 0-1. In 720x720dpi mode the transfer arrays in 
stcolor.ps limit the dot density to about 50%, so these arrays end at 0.5 (and
begin at 0.5 for RGB). Because of automatic normalization, these arrays can
also be used as coding arrays. But of course in the fs2 case mentioned above,
values from 0 to 127 will never be delivered to the algorithm, while values
128-255 are delivered for adjacent intervals.

To clarify the intended use of the three parameters (parameter groups), keep
this in mind:
   
       
      + ColorAdjustMatrix is never used when transferring gray values. This
        restricts it to what the name says: adjustment of colors, that is,
        correction for miscolored ink. Do not use it for saturation or
        brightness control.
      + ?transfer arrays control the values delivered to the driver, which in
        turn controls the ink quantity. Use these arrays to control saturation
        and brightness. In general these arrays are identical for all inks. If
        they differ they provide a simpler scheme for color correction, which
        is not necessarily faster than the ColorAdjustMatrix.
      + ?coding arrays control the color value intervals mapped to the internal
        color indices.
   
What is weaving?

The Epson Stylus Color has a head assembly that contains two physically
identifiable heads, one for black and one for cyan, magenta, and yellow (CMY).
This makes four "logical" heads, one for each color component. Each of these
four heads has several jets at some vertical (Y) distance from one another, so
several horizontal lines can be printed of a given color during one pass of the
heads. From experience I think there are fifteen jets per color, spaced at 1/
90in.

So the question arises of how to print at a Y resolution of 360dpi with 90dpi
jets. Simply by division one gets 360dpi/90dpi = 4, which tells us that 4
passes of the head assembly are needed to achieve a Y resolution of 360dpi.

Weaving is the method of how the fifteen jets are used to print adjacent
horizontal rows separated here by 1/360 inch:
   
    -----------------------------------------------------------------
              Print-head jets used with and without weaving          
    -----------------------------------------------------------------
                      Weaving                        noWeave         
             -------------------------      -------------------------
        Pass  1      2      3      4         1      2      3      4  
    Row                                                              
     0       jet     --     --     --       jet     --     --     -- 
              0                              0                       
     1        --    jet     --     --        --    jet     --     -- 
                     1                              0                
     2        --     --    jet     --        --     --    jet     -- 
                            2                              0         
     3        --     --     --    jet        --     --     --    jet 
                                   3                              0  
     4       jet     --     --     --       jet     --     --     -- 
              1                              1                       
     5        --    jet     --     --        --    jet     --     -- 
                     2                              1                
     6        --     --    jet     --        --     --    jet     -- 
                            3                              1         
    ...                                                              
   
Now let's assume that the dot diameter is different for each individual jet,
but the average among the jets matches the desired resolution. With weaving,
adjacent rows are printed by different jets, thus some averaging takes place.
Without weaving, adjacent rows are printed by the same jet and this makes the
dot diameter deviations visible as 1/90in stripes on the paper.

Print mode parameters

The parameters "Unidirectional", "Microweave", "noWeave", "OutputCode", "Model"
and the given resolution control the data generated for the printer.

Unidirectional

Simply toggles the unidirectional mode of the printer. Setting "Unidirectional"
definitely slows printing speed, but may improve the quality. I use this for
printing transparencies, where fast head movement could smear the ink.

Microweave, noWeave and OutputCode=deltarow

The first are two booleans, which implies that four combinations are possible.
Actually only three exist (if you don't count for deltarow): Softweave, 
Microweave, and noWeave. The first and second are functionally identical, the
difference being whether the driver or the printer does the job.

In the default Softweave mode the driver sends the data properly arranged to
the printer, while in Microweave mode, it is the printer that arranges the
data. But in general the host processor is much faster than the printer's
processor, and thus it is faster for the host do the job. In addition to that,
for 720dpi eight passes are required, and the amount of buffer space needed to
buffer the data for the passes is far beyond the printer's memory. Softweave
requires an odd value of "escp_Band"; the Stylus Color provides fifteen for
that.

"OutputCode" controls the encoding used. In the basic modes, the choice
consists of "plain" and "runlength". The computation of runlength-encoded data
does not take much time, less than the data tranfer to the printer; thus this
is the recommended mode, and of course the default. With the Stylus Color,
Epson introduced some new encoding principles, namely "tiff" and "deltarow".
While the first was omitted from this driver for lack of apparent advantages, "
deltarow" is available as an option. "Softweave" cannot be used with this
encoding, so if OutputCode=deltarow is set, Microweave becomes the default.
Maybe that the size of the ESC/P2 code becomes smaller, but I have never
observed faster printing speed. Things tend to become slower with deltarow
compared to Softweave.

Model

Some ESC/P2 printers such as the Stylus 800 do not offer Microweave or the
commands required to do Softweave. Setting Model just changes the defaults and
omits some parts of the initialization sequence which are not compatible with
the given printer model. Currently only "st800" is supported besides the
default stcolor.

Bugs and pitfalls

  * The given ?coding and ?transfer arrays should be strictly monotonic.
  * It is impossible to change WHITE: that's your paper. Thus RGB transfer
    should end at 1.0 and CMYK transfer should start at 0.0.
  * Usually 8 bits per component yields fastest operation.
  * The ColorAdjustMatrix is not used in the reverse transformation used when
    Ghostscript does the dithering (gs* modes). Expect funny results.
  * If BitsPerPixel is less than 6, the entire coding and transfer process does
    not work. This is always true for the gs* modes and becomes true for the
    other modes if BitsPerPixel is forced to low values.
  * 720×720dpi printing should never select the gs* modes and should always use
    stcolor.ps. (I prefer 360×720.)

Tests

This section gives an overview of performance in terms of processing and
printing times, from tests run after version 1.13. Printing was done offline
(simply copying a processed file to the printer) to measure real printing speed
without regard to speed of processing on the host, since at high resolutions,
processing time is the same order of magnitude and thus may become the limiting
factor.

The various OutputCodes

I ran several files though Ghostscript and recorded the size of the resulting
print code, the processing time, and the printing time, at least for some of
the files, always using these options:
   
    gs -sDEVICE=stcolor -sPAPERSIZE=a4 stcolor.ps - < file.ps

(Actually "-sPAPERSIZE=a4" is in my gs_init.ps since I'm a germ.)

"deltarow" is the new encoding principle ("ESC . 3 10 10 1") with Microweave
on. It is activated with "-sOutputCode=deltarow".

"Softweave" actually means that nothing else was used: it is the default, and
implies that odd v=40/h=10/m=15 mode ("ESC . 1 40 10 15").

"Microweave" means "-dMicroweave", equivalent to "ESC . 1 10 10 1", with full
skip optimization and microweave activated.

Finally I wanted to see the plain Kathy Ireland, and used "-sOutputCode=plain",
which just replaces runlength encoding (RLE) by no encoding, thus using "
ESC . 0 40 10 15". [So sorry ;-) Kathy was still dressed in blue in front of
the blue sea on a blue air cushion -- nice to see but hard to dither.]

So here are the results.
   
    --------------------------------------------------------------------------
           File sizes and printing speeds with various weaving methods        
    --------------------------------------------------------------------------
                  golfer.ps    colorcir.ps     drawing.ps         brief.ps    
    --------------------------------------------------------------------------
    deltarow     572751/       643374/       90142/46.180u/    178563/49.350u/
                 48.180u       41.690u       1:50              2:22           
    Softweave    559593/       669966/       296168/48.160u/   269808/43.320u/
                 46.810u       44.960u       1:30              1:55           
    Microweave   590999/       754276/       338885/47.060u/   282314/44.690u/
                 56.060u       42.890u       1:50              2:22           
   
    -------------------------------------
                Kathy Ireland            
    -------------------------------------
                         kathy.ps        
    -------------------------------------
    deltarow      3975334/111.940u/5:35  
    Softweave     3897112/101.940u/3:10  
    Microweave    4062829/100.990u/3:15  
    plain/soft    5072255/104.390u/3:05  
   
It may be that I've not chosen the optimal deltarow code, but even if it saves
at lot of bytes, printing-speed is not increased.

At least the printer prefers plain Kathy. In other words, sending 1 Megabyte or
20% more data has no impact on printing speed. drawing.ps is an exception to
this rule: plain prints slower than RLE.

"Unclever" coding -- especially with deltarow -- can significantly slow down
printing. But even if very significant advantages in the size of the code are
achieved, "deltarow" is not competitive. colorcir.ps shows savings with 
deltarow, but printing is a mess.

Printing time related to other options

Full page halftone images printed, unless otherwise noted.
   
    ---------------------------------------------------------------------------
                      Printing time related to other options                   
    ---------------------------------------------------------------------------
      dpi       Print mode     Size    Time   Comments                         
                                KB                                             
    ---------------------------------------------------------------------------
    180x180   mono     -/uni     358   1:15                                    
                        -/bi     358   0:45                                    
                      micro/     205   0:45   Not weaving                      
                          bi                                                   
                       soft/     179   1:25                                    
                          bi                                                   
              color     -/bi     641   2:45                                    
                       soft/     556   1:32                                    
                          bi                                                   
    360x360   mono     -/uni     269   0:50   Monochrome text                  
                        -/bi     269   0:35   Monochrome text                  
                      micro/     269   2:25   Monochrome text                  
                          bi                                                   
                       soft/     250   3:15   Monochrome text                  
                         uni                                                   
                       soft/     250   1:55   Monochrome text                  
                          bi                                                   
              color     -/bi     346   1:00   Sparse-color page, visible       
                                              displacements                    
                      micro/     346   1:50   Sparse-color page, looks buggy --
                          bi                  printer?                         
                       soft/     294   1:30   Sparse-color page, O.K.          
                          bi                                                   
                        -/bi    2218   2:45   Visible stripes                  
                      micro/    5171   3:17                                    
                          bi                                                   
                       soft/    3675   3:05                                    
                          bi                                                   
    360x720   mono     soft/    2761   5:40                                    
                          bi                                                   
              color    soft/    7789   6:15   Just a small difference!         
                          bi                                                   
    720x360   color    soft/    7182   5:40                                    
                          bi                                                   
    720x720   color   micro/   14748    30:   Actually beyond printer's        
                          bi             26   capabilities                     
                       soft/   14407    11:                                    
                          bi             08                                    
   
Acknowledgments

This driver was copied from gdevcdj.c (Ghostscript 3.12), which was contributed
by George Cameron, Koert Zeilstra, and Eckhard Rueggeberg. Some of the ESC/P2
code was drawn from Richard Brown's gdevescp.c. The POSIX interrupt code
(compilation option -DSTC_SIGNAL) is from Frederic Loyer. Several improvements
are based on discussions with Brian Converse, Bill Davidson, Gero Guenther,
Jason Patterson, ? Rueschstroer, and Steven Singer.

While I wish to thank everyone mentioned above, they are by no means
responsible for bugs in the stcolor driver -- just for the features.
Gunther Hess
Richard Wagner Strasse 112
D-47057 Duisburg
Germany
+49 203 376273 telephone (MET evening hours)
<ghess@elmos.de>
-------------------------------------------------------------------------------

uniprint, a flexible unified printer driver

uniprint is a unified parametric driver by Gunther Hess <ghess@elmos.de> for
several kinds of printers and devices, including
   
       
      + any Epson Stylus Color, Stylus, or Stylus Pro
      + HP PCL/RTL
      + Canon BubbleJet Color 610
      + NEC P2X
      + Sun raster file format
   
This driver is intended to become a unified printer driver. If you consider it
ugly, please send me your suggestions for improvements. The driver will be
updated with them. Thus the full explanation of the driver's name is:
   
    Ugly- -> Updated- -> Unified Printer Driver

But you probably want to know something about the functionality. At the time of
this writing uniprint drives:
   
   
  * NEC Pinwriter P2X (24-pin monochrome impact printer, ESC/P style)
  * Several Epson Stylus Color models (ESC/P2 style)
  * HP-DeskJet 550c (basic HP-RTL)
  * Canon BJC 610

It can be configured for various other printers without recompilation and
offers uncompressed (ugly) Sun rasterfiles as another format, but this format
is intended for testing purposes rather than real use. The usage of this driver
is quite simple. The typical command line looks like this:
   
    gs @{MODEL}.upp -sOutputFile={printable file} MyFile.ps -c quit

For example, from my Linux box:
   
    gs @stc.upp -sOutputFile=/dev/lp1 tiger.ps -c quit

    ---------------------------------------------------------------------------
           Unified Printer Parameter files distributed with Ghostscript        
    ---------------------------------------------------------------------------
    Canon BJC 610 (color, rendered)                                            
         bjc610a0.upp    360×360dpi    plain paper, high speed                 
         bjc610a1.upp    360×360dpi    plain paper                             
         bjc610a2.upp    360×360dpi    coated paper                            
         bjc610a3.upp    360×360dpi    transparency film                       
         bjc610a4.upp    360×360dpi    back print film                         
         bjc610a5.upp    360×360dpi    fabric sheet                            
         bjc610a6.upp    360×360dpi    glossy paper                            
         bjc610a7.upp    360×360dpi    high gloss film                         
         bjc610a8.upp    360×360dpi    high resolution paper                   
                                                                               
         bjc610b1.upp    720×720dpi    plain paper                             
         bjc610b2.upp    720×720dpi    coated paper                            
         bjc610b3.upp    720×720dpi    transparency film                       
         bjc610b4.upp    720×720dpi    back print film                         
         bjc610b6.upp    720×720dpi    glossy paper                            
         bjc610b7.upp    720×720dpi    high-gloss paper                        
         bjc610b8.upp    720×720dpi    high resolution paper                   
                                                                               
    HP Ink-Printers                                                            
         cdj550.upp      300×300dpi    32-bit CMYK                             
         cdj690.upp      300×300dpi    Normal mode                             
         cdj690ec.upp    300×300dpi    Economy mode                            
         dnj750c.upp     300×300dpi    Color -- also good for 450C             
         dnj750m.upp     600×600dpi    Monochrome                              
                                                                               
    NEC P2X                                                                    
         necp2x.upp      360×360dpi    8-bit (Floyd-Steinberg)                 
                                                                               
    Any Epson Stylus Color                                                     
         stcany.upp      360×360dpi    4-bit, PostScript halftoning            
         stcany_h.upp    720×720dpi    4-bit, PostScript halftoning            
                                                                               
    Original Epson Stylus and Stylus Pro Color                                 
         stc.upp         360×360dpi    32-bit CMYK, 15-pin                     
         stc_l.upp       360×360dpi    4-bit, PostScript halftoning, weaved    
                                       noWeave                                 
         stc_h.upp       720×720dpi    32-bit CMYK, 15-pin Weave               
                                                                               
    Epson Stylus Color II                                                      
         stc2.upp        360×360dpi    32-bit CMYK, 20-pin, Epson Stylus Color 
                                       II(s)                                   
         stc2_h.upp      720×720dpi    32-bit CMYK, 20-pin, Epson Stylus Color 
                                       II                                      
         stc2s_h.upp     720×720dpi    32-bit CMYK, 20-pin, Epson Stylus Color 
                                       IIs                                     
                                                                               
    Epson Stylus Color 200                                                     
         stc200.upp      360×720dpi    Plain Paper                             
                                                                               
    Epson Stylus Color 500 (good transfer curves for plain paper)              
         stc500p.upp     360×360dpi    32-bit CMYK, noWeave, plain paper       
         stc500ph.upp    720×720dpi    32-bit CMYK, noWeave, plain paper       
                                                                               
    Epson Stylus Color 600, 32/90-inch weaving                                 
         stc600pl.upp    360×360dpi    32-bit CMYK, 32-pin, plain paper        
         stc600p.upp     720×720dpi    32-bit CMYK, 32-pin, plain paper        
         stc600ih.upp    1440×         32-bit CMYK, 30-pin, inkjet paper       
                         720dpi                                                
                                                                               
    Epson Stylus Color 640                                                     
         stc640p.upp     720×720dpi    plain paper?                            
         st640p.upp      720×720dpi    CMYK, plain paper                       
         st640pg.upp     720×720dpi    grayscale, plain paper                  
         st640pl.upp     360×360dpi    CMYK, plain paper                       
         st640plg.upp    360×360dpi    grayscale, plain paper                  
         st640ih.upp     1440×         CMYK, inkjet paper                      
                         720dpi                                                
         st640ihg.upp    1440×         grayscale, inkjet paper                 
                         720dpi                                                
                                                                               
    Epson Stylus Color 800, 64/180-inch weaving                                
         stc800pl.upp    360×360dpi    32-bit CMYK, 64-pin, plain paper        
         stc800p.upp     720×720dpi    32-bit CMYK, 64-pin, plain paper        
         stc800ih.upp    1440×         32-bit CMYK, 62-pin, inkjet paper       
                         720dpi                                                
         stc1520.upp     1440×         32-bit CMYK, 62-pin, inkjet paper       
                         720dpi                                                
                                                                               
    Sun raster file                                                            
         ras1.upp        1-bit         monochrome (Ghostscript)                
         ras3.upp        3-bit         RGB (Ghostscript)                       
         ras4.upp        4-bit         CMYK (Ghostscript)                      
         ras8m.upp       8-bit         grayscale (Floyd-Steinberg)             
         ras24.upp       24-bit        RGB (Floyd-Steinberg)                   
         ras32.upp       32-bit        CMYK (CMYK-Floyd-Steinberg)             
   
Thanks to Danilo Beuche, Guido Classen, Mark Goldberg and Hans-Heinrich
Viehmann for providing the files for the stc200, hp690, stc500 and the stc640.
Thanks to Michael Lossin for the newer st640 parameter sets.

Please note the following:
   
       
      + Changing the resolution with Ghostscript's -r switch is usually not
        possible.
      + For Epson Stylus Color models not listed above, the two stc500 variants
        are likely to work in addition to stcany, but their gamma correction
        might be wrong.
   
The state of this driver

The coding of uniprint was triggered by the requirements of the various Stylus
Color models and some personal needs for HP and NEC drivers. Thus the Epson
models are well represented among the distributed parameter files. When this
driver entered the beta test phase, three other drivers appreared on the scene
that could be at least partially integrated into uniprint: cdj850 by Uli
Wortmann (available at http://www.erdw.ethz.ch/~bonk/hp850/hp850.html), hpdj by
Martin Lottermoser, and bjc610 by Helmut Riegler.

Uli addresses features of the more recent DeskJet models that will not be
available in uniprint soon. Martin taught me a lesson on HP-PCL3 headers that
will be available in uniprint soon. Helmut in turn followed an almost similar
idea, but targetted primarily for printing on Canon printers from the pbmplus
library. Starting with version 1.68 of uniprint, BJC support is available. Work
on the hpdj integration will start after the update of my website.

Notes on uniprint's background

uniprint is actually an update of stcolor, but much more versatile than its
predecessor; stcolor, in its turn, started as a clone of the color DeskJet
family of drivers (cdj*). Finally, cdj* can be considered an addition of
features to the simpler monochrome drivers of Ghostscript. This addition of
features is useful to get an idea of the functionality of uniprint:
   
    Monochrome to advanced color (cdj*):
        This adds color mapping and rendering functions to the driver. Error
        diffusion is especially important for the quality of printing.
   
    HP color to Epson Color (stcolor)
        The Epson Stylus Color offered two features simultaneously: it could
        produce 720×720dpi output and it could soak the paper. In other words,
        it required more color management features inside the driver. This is
        still the major conceptual difference in the data generation for HP and
        Epson printers.
   
    Weaving techniques (stcolor)
        Besides the internal color management, the Stylus Color did not provide
        enough buffer space to operate the printer fast at 720×720dpi. The use
        of weaving could yield triple the print speed. Weaving, also called
        interleaving, is present in some monochrome drivers too. The new thing
        in stcolor was the combination with error diffusion. Unfortunately the
        weaving was somehow hard-coded, as the problems with the newer members
        of the Stylus Color family of printers demonstrated.
   
    Generalized output format and weaving (uniprint)
        The features mentioned above yield about 90% of stcolor's source code;
        only 10% is related to the formatting of the output. The idea to make
        the output format switchable came up soon after completing stcolor, but
        its final design was triggered by the (personal) necessity to drive a
        NEC P2X and a Designjet 750c.
   
   
Thus uniprint accumulates almost any features that can be found among the other
printer drivers, which clearly has some disadvantage in processing speed --
true in particular of version 1.75, since it was targetted for functionality,
and several speed-gaining features were (knowingly) omitted.

To summarize and to introduce the terms used in the description of the
parameters, the features of uniprint that can be parameterized are:
   
       
      + color mapping,
      + color rendering (error diffusion or Floyd-Steinberg),
      + output format, including
      + weaving.
   
Godzilla's guide to the creation of Unified Printer Parameter (.upp) files

Here is one of the distributed parameter files (stc_l.upp) with some added
comments. Also see the section that describes all uniprint's parameters in
brief.
-supModel="Epson Stylus Color I (and PRO Series), 360x360DpI, noWeave"
-sDEVICE=uniprint                    -- Select the driver
-dNOPAUSE                            -- Useful with printers
-dSAFER                              -- Provides some security
-dupColorModel=/DeviceCMYK           -- Selects the color mapping
-dupRendering=/ErrorDiffusion        -- Selects the color rendering
-dupOutputFormat=/EscP2              -- Selects the output format
-r360x360                            -- Adjusts the resolution
-dupMargins="{ 9.0 39.96 9.0 9.0}"   -- Establishes (L/B/R/T margins in points)
-dupComponentBits="{1 1 1 1}"        -- Map: bits per component (default: 8)
-dupWeaveYPasses=4                   -- Weave: Y-passes (default: 1)
-dupOutputPins=15                    -- Format/weave: scans per Command
-dupBeginPageCommand="<              -- Goes to the printer
  1b40   1b40                        -- ESC '@' ESC '@'    -> dual reset
  1b2847 0100 01                     -- ESC '(' 'G' 1 0 1  -> graphics
  1b2869 0100 00                     -- ESC '(' 'i' 1 0 1  -> no HW weave
  1b2855 0100 0A                     -- ESC '(' 'U' 1 0 10 -> 360dpi
  1b5500                             -- ESC 'U'  0         -> bidir print
  1b2843 0200 0000                   -- ESC '(' 'C' 2 0 xx -> page length
  1b2863 0400 0000 0000              -- ESC '(' 'c' 4 0 xxxx -> margins
>"                                   -- as it is, unless:
-dupAdjustPageLengthCommand          -- Adjust page length in BOP requested
-dupAdjustTopMarginCommand           -- Adjust top margin in BOP
-dupAdjustBottomMarginCommand        -- Adjust bottom margin in BOP
-dupEndPageCommand="(\033@\014)"     -- Last (but one) data to the printer
-dupAbortCommand="(\033@\15\12\12\12\12    Printout-Aborted\15\014)"

That's short, and if one removes upWeaveYPasses and upOutputPins it becomes
shorter, almost stcany.upp. This miniature size is because I am most familiar
with ESC/P2, and was able to add defaults for the omitted parameters. Now a few
notes about the parameters used in this example:
   
   
  * upModel is a string serving as a comment (and nothing else).
  * DEVICE, NOPAUSE, SAFER are well-known Ghostscript parameters described in
    the usage documentation.
  * upColorModel is one of major uniprint parameters: it selects the color
    mapping and in turn the PostScript color model. It supports the devices /
    DeviceGray, /DeviceRGBW, /DeviceRGB, /DeviceCMYK, and /DeviceCMYKgenerate.
  * upRendering selects the (color) rendering, supporting the values /
    ErrorDiffusion and /FSCMYK32. /ErrorDiffusion is similar to fsmono, fsrgb
    and fsx4 of stcolor, while /FSCMYK32 is (almost) identical to fscmyk and 
    hscmyk, but is restricted to 32-bit data and should be used in conjunction
    with /DeviceCMYKgenerate.
  * upOutputFormat selects the output method, supporting the values /SunRaster,
    /Epson, /EscP2, /EscP2XY, and/Pcl.
        /           creates Sun raster files and requires no other parameters  
        SunRaster                                                              
        /Epson      is used for the elderly ESC/P format (used by many         
                    printers)                                                  
        /EscP2      is used by more recent Epson printers (no X weaving        
                    supported)                                                 
        /EscP2XY    supports X-Weaving, used with 1440dpi printers and in      
                    stc2s_h                                                    
        /Pcl        HP PCL/RTL-style output formatter without weaving          
       
   
  * -r360x360 is Ghostscript's standard resolution switch.
  * upMargins="{ 9.0 39.96 9.0 9.0}" has function similar to the Ghostscript
    parameter .HWMargins: it sets the left, bottom, right, and top margins in
    points. uniprint provides this parameter to enable automatic left-right
    exchange if upYFlip is active.
  * upComponentBits is an array of integers that selects the bits stored in
    raster memory, by default 8 bits per component. In this example, 1 bit is
    selected for each component, thus turning down the Floyd-Steinberg
    algorithm (but still carrying out the time-consuming computation). The
    related parameter "upComponentShift" controls positioning the components
    within raster memory. Each of the numbers given corresponds to a component
    which depends on the selected "upColorModel":
                /            /            /           /                /         
            DeviceGray   DeviceRGBW   DeviceRGB   DeviceCMYK   DeviceCMYKgenerate
        -------------------------------------------------------------------------
        0     White        White         Red        Black            Black       
        1       --          Red         Green        Cyan             Cyan       
        2       --         Green        Blue       Magenta          Magenta      
        3       --          Blue         --         Yellow           Yellow      
       
        This order may not be suitable for some printers, so another parameter
        "upOutputComponentOrder", also an array of integers, selects the output
        order using the numbers on the left.
       
   
    One group of very important parameters not used in the example above
    deserves to be mentioned here: the transfer arrays, named "up{color}
    Transfer", where {color} is one of the names in the table above. These are
    arrays of floats in the range 0.0 - 1.0 representing the color transfer
    functions. They are used during mapping and rendering. In the simplest
    case, these arrays ensure an equidistant distribution of the stored values
    within the device space (which means a nonlinear mapping from Ghostscript's
    point of view). If the given array does not cover the entire range from 0
    to 1, which applies for the Stylus Color family at high resolution for some
    media, only the relevant part gets mapped to raster memory (meaning that
    is's fully utilized) and the rendering takes care of the "overhang" (in
    this case the post-diffusion of 1-bit components makes sense).
   
    Finally an important note on the transfer arrays: for monochrome devices
    the stored component is White, which is the way PostScript defines these
    devices, but most printers require Black. Thus one has to provide a falling
    "upWhiteTransfer" for such printers.
   
  * upWeaveYPasses is an integer that gives the number of print head passes
    required to achieve the requested Ydpi. This makes sense only if
  * upOutputPins is set to something greater than 1. Thus multiple pins or
    nozzles are transferred with a single command, and of course such a command
    must be supported by the device.

If no other weave parameters are given, uniprint computes several defaults
which together do no weaving. The /Epson and /EscP2XY formats take care of "
upWeaveXPasses" too.
   
   
  * upBeginPageCommand represents the data transferred to the printer whenever
    a new page begins. Before that, "upBeginJobCommand" is written to the
    device only once per output file. (Intended for the HP PJL sequences).
  * upAdjustBottomMarginCommand, upAdjustMediaSize, upAdjustPageLengthCommand, 
    upAdjustPageWidthCommand, upAdjustResolutionCommand, and 
    upAdjustTopMarginCommand
   
    Normally uniprint does not change the "upBeginPageCommand", nor does it
    provide a default. However, if the above boolean values are set, the
    corresponding values are changed (provided that the code of the formatters
    supports this change and the commands to be adjusted are included in the
    BOP string).
   
  * upEndPageCommand is the fixed termination sequence for each page, and of
    course there is an "upEndJobCommand" too.
  * upAbortCommand is written if uniprint's interrupt detection is enabled and
    a signal is caught. It replaces "upEndPageCommand" and "upEndJobCommand",
    thus allowing the indication of an aborted job. (Ghostscript gets an error
    return from uniprint in this case, and abandons further processing.)

For the ESC/P(2) formats all commands represent binary data, while for the PCL/
RTL formatter some of them are formats for fprintf. These strings must
explicitly have a trailing "\0'.

I should write more, but the only recommendation is to take a look at the
various parameter files. Here are a few more hints.
   
   
  * If the Driver rejects a configuration, nothing happens until showpage; then
    an error is raised and a message with "CALL-REJECTED upd_print_page..." is
    printed on stderr.
  * uniprint has lots of messages that can be activated by setting bits in the
    preprocessor macro UPD_MESSAGES. I usually use the compile-time option 
    -DUPD_MESSAGES=0x17 for configuration development. (For the semantics,
    check the UPD_M_ macros in the source.)
  * A program "uninfo.ps" distributed with Ghostscript displays interactively
    in alphabetical order the contents of the current pagedevice dictionary.
    This includes any parameters generated or changed by uniprint.

All parameters in brief

This table gives a brief explanation of every parameter known to uniprint,
listing them in alphabetical order. "[ ]" denotes that a parameter is an array,
and "(RO)" that it is read-only.
   
    ---------------------------------------------------------------------------
                              All uniprint parameters                          
    ---------------------------------------------------------------------------
    Parameter                     Type        Use                              
    ---------------------------------------------------------------------------
    upAbortCommand                String      End of page and file on interrupt
    upAdjustBottomMarginCommand   Bool        Manipulate bottom margin in      
                                              upBeginPageCommand               
    upAdjustMediaSizeCommand      Bool        Manipulate Mediasize [intended]  
    upAdjustPageLengthCommand     Bool        Manipulate page length in        
                                              upBeginPageCommand               
    upAdjustPageWidthCommand      Bool        Manipulate page width in         
                                              upBeginPageCommand               
    upAdjustResolutionCommand     Bool        Manipulate resolution            
    upAdjustTopMarginCommand      Bool        Manipulate top margin in         
                                              upBeginPageCommand               
    upBeginJobCommand             String      Begin each output file           
    upBeginPageCommand            String      Begin each page                  
    upBlackTransfer               Float       Black transfer (CMYK only!)      
                                  [ ]                                          
    upBlueTransfer                Float       Blue transfer                    
                                  [ ]                                          
    upColorInfo                   Int[ ]      struct gx_device_color_info      
    upColorModel                  Name        Select color mapping             
    upColorModelInitialized       Bool        Color mapping OK                 
                                  (RO)                                         
    upComponentBits               Int[ ]      Bits stored per component        
    upComponentShift              Int[ ]      Positioning within gx_color_index
    upCyanTransfer                Float       Cyan transfer                    
                                  [ ]                                          
    upEndJobCommand               String      End each file unless             
                                              upAbortCommand                   
    upEndPageCommand              String      End each page unless             
                                              upAbortCommand                   
    upErrorDetected               Bool        Severe (VM) error, not fully     
                                  (RO)        operational                      
    upFSFixedDirection            Bool        Inhbits direction toggling in    
                                              rendering                        
    upFSProcessWhiteSpace         Bool        Causes white-space rendering     
    upFSReverseDirection          Bool        Run rendering in reverse (if     
                                              fixed)                           
    upFSZeroInit                  Bool        Non-random rendering             
                                              initialization                   
    upFormatXabsolute             Bool        Write absolute X coordinates     
    upFormatYabsolute             Bool        Write absolute Y coordinates     
    upGreenTransfer               Float       Green transfer                   
                                  [ ]                                          
    upMagentaTransfer             Float       Magenta transfer                 
                                  [ ]                                          
    upMargins                     Float       L/B/R/T margins in points        
                                  [ ]                                          
    upModel                       String      Comment string, holds some info  
    upOutputAborted               Bool        Caught an interrupt              
                                  (RO)                                         
    upOutputBuffers               Int         Number of rendering buffers (2^N)
    upOutputComponentOrder        Int[ ]      Order of components when printing
    upOutputComponents            Int         Number of written components, not
                                              fully operational                
    upOutputFormat                Name        Select output format             
    upOutputFormatInitialized     Bool        Format data OK                   
                                  (RO)                                         
    upOutputHeight                Int         Output height in pixels          
    upOutputPins                  Int         Number of pins / nozzles per     
                                              command                          
    upOutputWidth                 Int         Output width in pixels           
    upOutputXOffset               Int         Offset in pixels, if             
                                              upFormatXabsolute                
    upOutputXStep                 Int         Divisor or multiplier for X      
                                              coords                           
    upOutputYOffset               Int         Offset in pixels, if             
                                              upFormatYabsolute                
    upOutputYStep                 Int         Divisor or multiplier for Y      
                                              coords                           
    upRasterBufferInitialized     Bool        GS buffer OK                     
                                  (RO)                                         
    upRedTransfer                 Float       Red transfer                     
                                  [ ]                                          
    upRendering                   Name        Select rendering algorithm       
    upRenderingInitialized        Bool        Rendering parameters OK          
                                  (RO)                                         
    upSelectComponentCommands     String      Establish color (output order!)  
                                  [ ]                                          
    upSetLineFeedCommand          String      Adjust linefeed (Epson only)     
    upVersion                     String      Source code version              
                                  (RO)                                         
    upWeaveFinalPins              Int[ ]      Number of bottom pins on EOP     
                                              passes                           
    upWeaveFinalScan              Int         Begin EOP passes (Y-coord)       
    upWeaveFinalXStarts           Int[ ]      X-pass indices for EOP passes    
    upWeaveFinalYFeeds            Int[ ]      Y increments for EOP passes      
    upWeaveInitialPins            Int[ ]      Number of top pins on BOP passes 
    upWeaveInitialScan            Int         End BOP passes (Y coord)         
    upWeaveInitialXStarts         Int[ ]      X-pass indices for BOP passes    
    upWeaveInitialYFeeds          int[ ]      Y increments for BOP passes      
    upWeavePasses                 Int         XPasses × YPasses                
    upWeaveXPasses                Int         Number of X passes               
    upWeaveXStarts                Int[ ]      X-pass indices for normal passes 
    upWeaveYFeeds                 Int[ ]      Y increments for normal passes   
    upWeaveYOffset                Int         Number of blank or incomplete    
                                              scans at BOP                     
    upWeaveYPasses                Int         Number of X passes               
    upWhiteTransfer               Float       White transfer (monochrome       
                                  [ ]         devices!)                        
    upWriteComponentCommands      String      Commands to write each component 
                                  [ ]                                          
    upWroteData                   Bool        Something (BeginJob) written to  
                                  (RO)        output                           
    upXMoveCommand                String      X positioning command            
    upXStepCommand                String      Single step to the right         
    upYFlip                       Bool        Flips output along the Y axis    
    upYMoveCommand                String      Y positioning command            
    upYStepCommand                String      Single step down                 
    upYellowTransfer              Float       Yellow transfer                  
                                  [ ]                                          
   
uniprint's Roll of Honor

I should mention all of the people who were involved in stcolor's evolution,
but I've decided to start from scratch here for uniprint:
   
    John P. Beale
        for testing the stc600 modes
    Bill Davidson
        who triggered some weaving research and tested stc2s_h
    L. Peter Deutsch
        who triggered ease of configuration
    Mark Goldberg
        who prepared the stc500 transfers
    Scott F. Johnston and Scott J. Kramer
        for testing the stc800 modes
    Martin Lottermoser
        for his great commented H-P DeskJet driver
    Helmut Riegler
        for the BJC extension
    Hans-Gerd Straeter
        for some measured transfer curves and more
    Uli Wortmann
        for discussions and his cdj850 driver
    My family
        for tolerating my printer-driver hacking
   
   

Gunther Hess
Duesseldorfer Landstr. 16b
D-47249 Duisburg
Germany
+49 203 376273 telephone (MET evening hours)
<ghess@elmos.de>
-------------------------------------------------------------------------------

Sun SPARCprinter

This section was contributed by Martin Schulte.

With a SPARCprinter you always buy software that enables you to do PostScript
printing on it. A page image is composed on the host, which sends a bitmap to
the SPARCprinter through a special SBUS video interface. So the need for a
Ghostscript interface to the SPARCPrinter seems low, but on the other hand,
Sun's software prints some PostScript drawings incorrectly: some pages contain
a thin vertical line of rubbish, and on some Mathematica drawings the text at
the axes isn't rotated. Ghostscript, however, gives the correct results.
Moreover, 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 shown
here.

Installation

Add sparc.dev to DEVICE_DEVS and compile Ghostscript as described in the
documentation on how to build Ghostscript. Afterwards you can use the following
script as an example for printing after modifying it with the right pathnames
-- including for {GSPATH} the full pathname of the Ghostscript executable:
   
    outcmd1='/vol/local/lib/troff2/psxlate -r'
    outcmd2='{GSPATH} -sDEVICE=sparc -sOUTPUTFILE=/dev/lpvi0 -'
    
    if [ $# -eq 0 ]
    then
      $outcmd1 | $outcmd2
    else
      cat $* | $outcmd1 | $outcmd2
    fi
   
Problems

Since /dev/lpi can be opened only for exclusive use, if another job has it open
(engine_ctl_sparc or another Ghostscript are the most likely candidates),
Ghostscript stops with "Error: /invalidfileaccess in --.outputpage--"

In case of common printer problems like being out of paper, a warning
describing the reason is printed to stdout. The driver tries access again each
five seconds. Due to a problem with the device driver (in the kernel) the
reason for printer failure isn't always reported correctly to the program. This
is the case, for instance, if you open the top cover (error E5 on the printer's
display). Look at the display on the printer itself if a "Printer problem with
unknown reason" is reported. Fatal errors cause the print job to be terminated.
-------------------------------------------------------------------------------

Apple dot matrix printer

This section was contributed by Mark Wedel <master@cats.ucsc.edu>.

The Apple Dot Matrix Printer (DMP) was a parallel predecessor to the
Imagewriter printer. As far as I know, Imagewriter commands are a superset of
the Dot Matrix printer's, so the driver should generate output that can be
printed on Imagewriters.

To print images, the driver sets the printer for unidirectional printing and 15
characters per inch (cpi), or 120dpi. It sets the line feed to 1/9 inch. When
finished, it sets the printer to bidirectional printing, 1/8-inch line feeds,
and 12 cpi. There appears to be no way to reset the printer 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 carriage return exclusively. Ensure that the Unix printer daemon
handles 8-bit (binary) data properly; in my SunOS 4.1.1 printcap file the
string "ms=pass8,-opost" works fine for this.

Finally, you can search devdemp.c for "Init" and "Reset" to find the strings
that initialize the printer and reset things when finished, and change them to
meet your needs.
-------------------------------------------------------------------------------

Copyright © 1996, 2000 Aladdin Enterprises. All rights reserved.

This file is part of AFPL Ghostscript. See the Aladdin Free Public License (the
"License") for full details of the terms of using, copying, modifying, and
redistributing AFPL Ghostscript.

Ghostscript version 6.50, 2 December 2000
