Poor print quality with Well Tempered Screens or ICM
Posted by: jacobmj ()
Date: May 03, 2012 12:13PM


I'm using a Magicolor 2200DL. I happen to be on Ubuntu 11.04,
and have installed per the instructions given on the foo2zjs
site. Additionally, I have installed ghostscript 8.71 as
/usr/bin/gs.foo. Without this, using gs 9.01, the printer
produces only gibberish, or never outputs a page.

I use an ICM file I created for my printer, and this is installed
as user1.icm. I should note that the provided Magicolor 2200 ICM
color profile is vastly incorrect for my printer. Mine works
well for me.

My issue now is with regards to Color Modes and Halftone
algorithms. I have been set to "Color - use ICM profile",
and "Well Tempered Screens (best)". My understanding of the
foo2zjs website and documentation suggests that this would be the
best setting. I find that the print quality is terrible. The
background of colored lineart is scattered with colored dots, and
the line edges are very fuzzy. To me, it's like I applied very
low-rate JPEG compression to all images. Even solid-black images
demonstrate a moire pattern.

I've had better luck with "Accurate Screens (better)". This reduces
the amount of "background" printed behind lineart images--but does not
entirely eliminate it.

A larger improvement, particularly on being able to produce solid
black images, results from using the color mode "Color - Graphics and
Text". This results in a smooth, black image.

Before I begin attaching photographs of the printout, can anyone shed
light on this behavior? Are these known bugs?

What are the "right" print settings?


Edited 1 time(s). Last edit at 05/03/2012 12:15PM by jacobmj.

Re: Poor print quality with Well Tempered Screens or ICM
Posted by: jacobmj ()
Date: May 03, 2012 12:25PM

One other note: When I select WTS halftoning, I do not get
K-plane optimization. The printer runs through all toners for
pages that consist entirely of black text. The statement

"The original ICM-based method uses the manufacturer-supplied ICM
color profiles and converts those to CRD's on the fly. This
method is the fastest. But it requires Well Tempored Screening,
e.g. ghostscript 8.54 or better. The advantages of the ICM method
are that its the fastest of the two methods, and it often allows
the foo2lava engine to optimize monochrome output on a color
queue to printing just the K plane."

on the foo2zjs page doesn't appear to be correct for me. Am I
inadvertently using CRDs? How would I know or select this mode?
I can't find any reference in the documentation.


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