Subject: Printing question (was Re: [netatalk-admins] PPD files on server)
From: PayPC System Mail Subscriber (spammail@quanta.paypc.com)
Date: Sun Mar 28 1999 - 04:00:54 EST
Thanks Jeremy, for the excellent summary of how to setup LPR printers under
LaserWriter 8.5.1-8.6.1
I myself have used that technique, but you spared me the hassle of writing
how to do it for my other users! :)
I have a question the printer gods on the list can probably answer (I'm sorry
it's not netatalk-specific, but I have no other people I can ask within easy
reach).
It's such an annoying little problem too, I'm sure someone has a ready answer
that's super-obvious to the DTP guys.
Environment:
OS 8.5.1, ColorSync 2.5.1, Viewsonic G810, configured for 9300 K white point,
1.8 gamma, LaserWriter 8.6, with HP's Laserjet 8.6 PPDs. Printer is an HP
Laserjet 4M [PostScript Rev 2011.110, 6MB RAM] 600 dpi.
Application:
Adobe Photoshop 5.0.2, properly informed of my ColorSync profile.
Here's what I do:
I take an image [it's just like a driver's licence photo -- medium light
background, head-shot, brightness and contrast corrected on my Viewsonic 810
display. It's 100 dpi and is Grayscale.
Problem:
When I print it using "default printer screens" as-is, I get a "correct"
looking printout, but it's "grainy" like a cheap newsletter picture.... I
suspect it's because it's using 83 lpi screen or something worse.
Now, the real problem comes when I try to be "clever" and do the bitmap
conversion myself. I've tried probably 80 different ways....
from Diffusion Dithering [which seems to do a correct job of converting the
levels to perceptual "levels" look at as a whole] but alas it prints out
HORRIBLY dark. And the "medium light" background [even though the diffusion
dither is also "medium light" in overall tone, gets printed out as SOLID
BLACK!
OK, so then I try doing my own screens, however, aside from the 83 lpi
setting, I can't find one that doesn't leave "tartan plaid" artifacts in the
image. I'm using diamond shaped, 45 degree, and yes, I've done the Sqrt(2)
conversion factor, etc.... Theoretically, 141 lpi should be the optimal lpi
for my image, no? (100 dpi input, 600 dpi resulting bitmap).
Does anyone have any advice for screen angles/lpi or a program to calculate
these quickly and optimally for: 1) image dpi, 2) target device dpi, etc. I
am quite sure this is a blacker "art" than SCSI, but I imagine the print guys
have figured out the basics.
When I MASSIVELY adjust the "Levels" of the image prior to using Diffusion
Dithering, (making the image almost totally washed out white), the printout
just STARTS to get close to be overall recognisable, but it's still quite
poor in quality.
What am I missing here? Is my PPD bad? In all of my tests, I have "Smooth
Graphics OFF" and HP's Resolution Enhancing Technology OFF. I also have
Black & White Colour Matching (as opposed to Colour/Grayscale).
I am almost tempted to write a PCL raster test program to see if it's
something the printer engine is doing [unlikely] or some weird-ass
interaction with PostScript and/or the LaserWriter driver [more likely].
Thanks for any help you guys can share,
=Rob=
This archive was generated by hypermail 2b28 : Sat Dec 18 1999 - 16:16:30 EST