Re: Gutenprint 5.0.0b2
Re: Gutenprint 5.0.0b2
- Subject: Re: Gutenprint 5.0.0b2
- From: Robert L Krawitz <email@hidden>
- Date: Mon, 7 Mar 2005 19:39:11 -0500
Date: Mon, 7 Mar 2005 15:24:25 -0500
From: Kurt Seefeldt <email@hidden>
I've been using Gutenprint 5.0.0b2 with my networked Epson 1280 on
OS X for several weeks and have enjoyed the control this driver
provides over that of the Epson driver. Does anyone know where I
can find documentation on all the features? In particular, GCR
settings and Linear Contrast Adjustment. I set GCR Limit to 1.000
so I can get good blacks, but don't know what the other related
limits are nor how to best tweak these.
Unfortunately, there is no written documentation on this, but I'm the
project lead. Let me know what specific ones you're interested in,
and I'll help you out.
Linear Contrast Adjustment is an alternate contrast adjustment when
contrast is less than 1 (when contrast is >= 1 there's no difference).
Rather than using an S curve flattened in the midrange, it uses a line
with slope less than 1 (thereby changing the black and white points).
This may be useful when printing photographs full bleed, where it
gives an even reduction in contrast across the entire image, but it's
not likely to be of much use for other purposes.
GCR Transition is the inverse exponent of the GCR curve, so it affects
how quickly the CMY->K transition kicks in. If the value is low, very
little black is used low in the curve. This gives a smoother
transition at the expense of more ink (and perhaps more muddiness) in
the midtones.
GCR Lower Bound and GCR Upper Bound control where in the linearized
output space black is first substituted for CMY (lower bound) and when
only black ink is used (upper bound). For example, if the upper bound
is .5, then whenever the gray component is more than 50% only black
ink is used. Note that the 50% level won't correspond to a value of
128 -- this conversion is done after linearization.
Other controls you might be interested in are Light Cyan Transition,
Light Magenta Transition, and Gray Transition, which control the
relative darknesses of the light inks, and Interleave Method which
gives you a few different options that may affect microbanding. I
assume you're aware that you need to use Manual Control for the
Quality and Image Type options.
Also, are you using 5.0-beta2 or 5.0-beta3? 5.0-beta3 (which is the
first version officially named Gutenprint) has some changes to the
color correction that we think improve the output quality that you
might like to try.
Please let me know your experiences with the driver and any
improvements you think we should make.
--
Robert Krawitz <email@hidden>
Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2
Member of the League for Programming Freedom -- mail email@hidden
Project lead for Gimp Print -- http://gimp-print.sourceforge.net
"Linux doesn't dictate how I work, I dictate how Linux works."
--Eric Crampton
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