Preliminary HP_DeskJet driver which supports HP 500C

Copyright 1985-1991  Commodore-Amiga, Inc.  All Rights Reserved


For Testing and Personal Use Only


This is an preliminary version of the HP_DeskJet printer driver which
also supports the HP 500C printer.

This preliminary version looks at your PrinterGFX Preferences
Threshold setting when doing a color graphic dump and applies a brightness
correction (lightening of the output) as listed below, based on your
Preferences threshold setting of 1 to 15.  In addition, a correction
to make CYAN one step lighter is applied.  On a greyscale graphic
dump, a fixed brightness correction is applied.  In either case
(color or greyscale), a threshold value of 1 will cause NO correction
to be applied.

Please test and see if any of these corrections are to your liking.
We suggest you select both Blue and Green color correction in Preferences.
Our inhouse tester and our developer helper/tester (Roger Uzun) found
enhanced -4 (currently threshold 10) to be best.  (Art Department Pro
users - see the note later on).


Some additional tips from Roger Uzun who helped develop the driver
==================================================================
1) For most color graphics, a setting of threshold = 10
   gives best results (or whatever that table is in the final
   version, currently thresh=10 is best)
2) For all color graphics using halftone dithering, with Red Color
   Correction OFF and Green and Blue Color Correction on,
     gives best results.
3) Color Graphics are not vibrant on normal or bond paper, use
   Paintjet paper (Clay Coated) for good color graphics.
4) Use Density = 7 for Color Graphics on Paintjet Paper,
   Density=6 for color graphics on normal paper.
5) For Grey Scale use Density = 7, halftone dithering for best results.

Basically, set threshold to 10, density to 7, dither to halftone,
Turn Red Color Correction OFF, Green and Blue Color Correction ON,
and forget about it.  Graphics will print out great all the time.

One caveat, when running low on Ink in a color cartridge, color balance
goes wacky, but not too wacky, so it makes it look like something
is wrong with the driver or program.  In fact replacing the ink cartridge
is in order, run a self test and you can see if the cartridge is going
south.

-Roger



NOTE - These driver-applied corrections will have NO impact if
you have Floyd-Stienberg dithering selected.  In addition, if you
select Threshold value 1, there will be no corrections applied.


NOTE FOR ART DEPARTMENT PROFESSIONAL USERS
==========================================
If you are using a package with its own enhanced printing support
such as Art Department Professional by ASDG, you will probably want
to turn off all corrections and set the Threshold to 1 when you do
color or greyscale graphic dumps.  Otherwise, the driver corrections
will cause interference with the internal dithering and corrections
applied by ADPro.



These are the brightness corrections as controlled via Threshold:
(skip ahead for more info on other driver featues)

* Lightening for grayscale printouts
* no correction if threshold = 1
	DC.B 	0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15	
* hard-coded correction otherwise
	DC.B    0,1,1,2,3,3,4,5,5,6,7,8,9,11,13,15

(note - there are two extra no-correction tables here in driver)

* Lightening for color printouts (CYAN correction uses threshold + 2)
* 1 = no correction (Threshold 1 means NO CORRECTION on any color)
	DC.B 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
* 2 = no correction (but CYAN gets corrected with table 4)
	DC.B 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
* 3 = no correction (but CYAN gets corrected with table 5)
	DC.B 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15

* 4 = enhanced linear -1 (CYAN uses table 5, etc.)
	DC.B 0,1,2,3,4,4,5,6,7,8,9,10,11,12,13,14
* 5 = linear -1
	DC.B 0,1,1,2,3,4,5,6,7,8,9,10,11,12,13,14

* 6 = enhanced linear -2
	DC.B 0,1,2,2,3,3,4,5,6,7,8,9,10,11,12,13
* 7 = linear -2
	DC.B 0,1,1,2,2,3,4,5,6,7,8,9,10,11,12,13

* 8 = enhanced linear -3
	DC.B 0,1,1,2,2,3,3,4,5,6,7,8,9,10,11,12
* 9 = linear -3
	DC.B 0,1,1,1,2,2,3,4,5,6,7,8,9,10,11,12

* 10= enhanced linear -4
	DC.B 0,1,1,2,2,3,4,5,5,6,6,7,8,9,10,11
* 11= linear -4
	DC.B 0,1,1,1,2,2,3,3,4,5,6,7,8,9,10,11

* 12= enhanced linear -5
	DC.B 0,1,1,2,2,3,3,4,5,5,5,6,7,8,9,10
* 13= linear -5
	DC.B 0,1,1,1,2,2,2,3,3,4,5,6,7,8,9,10

* 14= enhanced linear -6
	DC.B 0,1,1,1,2,2,3,3,3,4,4,5,6,7,8,9
* 15= linear -6
	DC.B 0,1,1,1,1,2,2,2,3,3,4,5,6,7,8,9

* 16= enhanced linear -7 (for CYAN when threshold is 14)
	DC.B 0,1,1,1,2,2,2,3,3,3,4,4,5,6,7,8
* 17= linear -7 (for CYAN when threshold is 15)
	DC.B 0,1,1,1,1,2,2,2,3,3,3,4,5,6,7,8

The enhanced corrections are hand adjusted correction tables
which are partway between linear and gamma correction.  These tables
were developed by Roger Uzun.



Here is information about the other features of this driver.

---------------------------- original readme --------------------------------
This HP_DeskJet driver is suitable for the DeskJet, DeskJet Plus, DeskJet 500
and DeskJet 500C printers. The driver has been tested with both the 500C
and original DeskJet printer.

For the 500C both color and B&W graphics are supported. For compatibility
the maximum number of dots vertically is 3000 (at 300 DPI) when US Letter
papersize is specified. Select CUSTOM as papersize to get 3100 dots vertically.
For color graphics, 3065 dots (at 300 DPI) is used for both US Letter and CUSTOM
printer preferences. Other paper sizes are calculated as before.


The density settings over 4 control shingling and depletion:

/* Set Shingling and Depletion according to density:
 *
 * 1-3: No depeletion, no shingling (75, 100, 150 DPI)
 *   4: 25% depletion, no shingling (300 DPI)
 *   5: 25% depletion, 50% shingling
 *   6: 25% depletion, 25% shingling
 *   7: No depletion, 25% shingling
 *
 * Use density 7 for transparancies.
 *
 * Depletion is ignored in B&W mode on all models.
 */

Support for DINA4 and US Legal paper sizes tested and seems OK.

Ewout
