   A printer driver for the HP670, HP690, HP850, HP855
   HP870, HP890, HP1100 and HP1600 color printers. 
   To be used with the ghostscript printing system.
   These drivers are currently not in the official distrib.
   Please report all problems to uli@bonk.ethz.ch 

   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.

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

    Copyright (C) 1996-1998  <Uli Wortmann uli@bonk.ethz.ch>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

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

   11.11.96. Initial release of the driver 

   25.08.97  Version 1.2. Resolved all but one of the 
                          known bugs, introduced a couple
			  of perfomance improvements. Complete
			  new color-transfer-function handling.
			  (see gamma).

  01.06.98   Version 1.3  Due to the most welcome contribution
                          of Martin 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 diver needs no longer special switches to be invoked
  except -sDEVICE=cdj850, or -sDEVICE=CDJ890, or sDEVICE=CDJ670
  or -sDevice=CDJ1600

  The hp690 is supported through the hp670 device, the hp855, hp870 
  and the hp1100 trough the hp850 device.

  The following switches are supported.

   -dPapertype= 0  plain paper [default]
                1  bond paper
		2  special paper
		3  glossy film
		4  transparency film

		Note, currently the lookuptables are not suited
		for printing on special paper or transperencies.
		Please revert to the gamma functions in this case.

   -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. overhead sheets), 
	      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
	      1.0 and less 10.0. To adjust individual gamma-values,
	      you have to additionally set MasterGamma to a value
	      greater 1.0 and less 10.0
	      
	      With the next release, gamma functions will be dropped.

   When using the driver, be aware that printing in 600dpi involves
   processing of 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 yoy 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 beeing, use the cdj550 device with -sBitsPerPixel=3
   for fast proof-prints. If you simply want to print 600dpi b/w 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 continuos
   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 to light
   for your business-graphs, or for overhead-sheets, feel free to set
   -dMasterGamma=1.7.

   Furthermore, you may tweak the gammavalues 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.

   If you want to learn more about gamma, see:
              
       ftp://ftp.igd.fhg.de/pub/doc/colour/GammaFAQ.pdf

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

   Have fun!

	Uli

	uli@bonk.ethz.ch
	http://bonk.ethz.ch

   Note: Depending on how you transfered the files, 
   you might need to remove some CR-codes used on intel-based machines:

   simply type:  unzip -a hp850.zip

   to compile with gs5.x, simply add 

             DEVICE_DEVS4=cdj850.dev cdj670.dev cdj890.dev cdj1600.dev

   to your makefile. 

   BTW, it is always a good idea to read make.txt found in the
   gs-distrib before attempting to recompile.....

