RE: Inkjet Ink restrictions
RE: Inkjet Ink restrictions
- Subject: RE: Inkjet Ink restrictions
- From: Mike Strickler <email@hidden>
- Date: Tue, 3 Jun 2008 09:10:36 -0700
The RIP manufacturers, strangely, seem to have no interest in
resolving this "art"
of creating initial ink restrictions as the base for creating a
profile.
It's all done by eyeball, with predictably unpredictable results.
Well, yes and no. Some RIPs come with a number of media presets and
even profiles. One problem for the user is that many RIP vendors are
actually deeply into the business of selling paper, so there's a lot
of incentive to provide the settings for those papers and no others.
As far as the ease of the process is concerned, some RIPs just show
density curves, which can be problematic as they don't accurately
reflect the hues and hue changes of the specific printer's inks. Some
RIPs do show the hue hooks, and this makes channel limiting pretty
easy. EFI Colorproof XF (successor to BestColor) does the whole thing
for you automatically, including TIL (though here it can help to make
a first guess to put you in the range) but also gives plenty of
visual aids (including the Lab curves) and full manualcontrol for
overriding the auto ink limiting. It even lets you choose a reference
profile to limit your gamut to. Caldera also has wizard-based ink
limiting and a pretty large selection of preset linearizations and
profiles for different papers. These are just two examples. But I
agree, this should be the general case, and I suspect before long it
will be.
I would like to see a method of generating initial ink restrictions
based on
density values and some form of gray balance throughout the
linearization
range. This would be somewhat difficult, as different materials have
different ink absorption and drying characteristics. But some
research by
those REALLY SMART GUYS could figure out an algorithm, I believe.
Ink limiting and gray balance are related but also distinct. You can
be gray-balanced at the limits and severely unbalanced everywhere
else--and surely will be without some additional curving of the
input. You can also be perfectly linearized in each channel but still
not gray-balanced. Some RIPs make an attempt to reconcile and gray-
balance the curves and others not at all, leaving it to the profile
to do the rest.
It might be very cool to compile a list of RIPs and their various ink-
limiting and linearization methods/features so we can compare.
Anybody want to start a speadsheet?
In the photographic world of the Lambda and Lightjet, Fuji and
Kodak publish
aim point densities for their different photographic materials.
There are
specified photographic density aim points for every step on the
scale. The
RIP then does the best job it can to achieve these target
densities. This
has several added benefits:
1. It means that ICC profiles generated on one machine will work on
another
machine.
2. It means that one can re-linearize without changing the target
densities,
thus eliminating the need to re-characterize.
3. It means that nearly all machines in the world are calibrated to
a nearly
identical standard, and can print the same image nearly identically. A
linearization on an inkjet machine will typically create green-cyan
shadows,
and magenta highlights. A linearization on a Lambda will create a
nearly
perfect gray scale throughout the range!
4. It means that if you have 3 Lambdas or Lighjets in your working
environment, one can be substituted for the other with nearly no color
change.
Those four points seem to be a big workflow incentive! Now how can
we get
RIP makers to work on it?
By getting everybody to to use the same media?
Mike Strickler
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