This is a preliminary version of a HP550C printer driver for PageStream.
It allows printing of CYMK documents which means that black will be 
printed as true black (from the black cartridge) instead of composite
black (from the color cartridge).  It also provides options for controlling
depletion and shingling, as well as grey scale printing without changing
printer drivers.

Since the "Resolution" indicators are used for controlling depletion and
shingling rates, this driver prints only in 300 dpi.

To install the driver, simply copy DJ550C.printer to the Printers drawer
of your PageStream directory.  

The resolution indicator is used to control B&W, shingling, and depletion
as follows:

  1-  B&W only printing (allows grey scale) - no shingling or depletion
  2-  Color Depletion at level 2 (25%), shingling at level 0 (NONE)
  3-  Color Depletion at level 3 (50%), shingling at level 0 (NONE)
  4-  Color Depletion at level 2 (25%), shingling at level 1 (50% - 2 pass)
  5-  Color Depletion at level 3 (50%), shingling at level 1 (50% - 2 pass)
  6-  Color Depletion at level 2 (25%), shingling at level 2 (25% - 4 pass)
  7-  Color Depletion at level 3 (50%), shingling at level 2 (25% - 4 pass)

Depletion is an algorithm applied to an incoming graphics image where a
selected percentage of pixels are removed from the image in order to enhance
the quality of the printed results.  Depletion reduces the volume of ink
applied to the print media.  As the level of depletion is increased there
will be a noticeable effect on the color intensity of the printed image.
Experimentation may be required to obtain the best results with a particular
graphic image.

The 25% and 50% depletion values do not indicate the percentage of dots
removed from the graphics image, but rather refers to a variable in the
depletion algorithm

The "no depletion" value is not provided for color images since there is
not enough combinations available out of seven numbers and HP recommends
the 25% depletion as the color graphics default.

Shingling is a process for printing complex or dense graphics images which
might otherwise cause problems with excessive ink, including color bleeding
or ink blooming on the print media.  The algorithm used by the DeskJet is
useful for complex color images where dots of different colors are being
laid down in close proximity to obtain an effective shade of some other
color.

The disadvantage of shingling is that the higher shingling value will
take longer to print than with shingling turned off.

Another factor that controls the print quality is the keyboard setting of
draft or high.  The driver is set up to accept whatever keyboard setting
is made for print quality.

This driver also corrects some problems that were present in the 500C driver
that was provided with PageStream.  Most notably, the graphics will be placed
on the page correctly.  The 500C driver lowered the graphics by about 3/8 of
an inch which made printing to a pre-printed form difficult.

The driver also determines whether run-length encoding is best for any 
particular graphics row.  If the run-length encoded width of the row is
larger than the un-encoded width, no compression takes place for that
row.  The 500C driver, which ALWAYS used run-length encoding has problems
printing very dense pictures over the width of the page.  The run-encoded
length could be almost twice the size of the un-encoded image which is
not handled properly on the 550C.

The 550C driver also issues a reset both at the begining and end of the
job.  This facilitates using other drivers so that a known condition
exists when these drivers start printing.

Again, please note that this is a very preliminary version of the driver.
More work needs to be done in testing the driver and adding/changing some
of the options.  Since there appeared to be a need to get a driver out as
soon as possible, I have decided to release it in its current form.  Please
report any problems or suggestions to:

				John Zacharias
				10004 Vanguard Drive
				Sacramento, CA 95827
				(916) 363-9153