Semi random start point for calibrating most RIPS
Semi random start point for calibrating most RIPS
- Subject: Semi random start point for calibrating most RIPS
- From: "Mark Rice" <email@hidden>
- Date: Sat, 31 May 2008 15:49:07 -0400
Here is the official point of view from the major software contact at a
major inkjet printer manufacturer. I have worked with this guy in the past,
and he does produce good results. However, I think you will see from reading
this that the starting point for calibrating most RIPS - i.e., setting the
ink restrictions - is extremely subjective and non-scientific. For those of
you out there that expressed concerns with non-objective comments, I think
this problem is the most high priority one - after all, RIPS are expensive,
drive the most volume, and we probably expect the greatest quality from
them.
Here it is:
" In my opinion,
Setting the initial ink restrictions is THE critical aspect of profiling
outdoor media.
Unfortunately, this is not an exact science and requires some practice and
some degree of 'art'.
I have run initial ink restrictions for SOME colors (particularly C and Y)
down in the 40s for some media, still getting good color, depending on the
medias ability to absorb/adsorb ink.
The key to getting good grey balance is to match up the density curves for C
and M. i.e. same density, same slope.
In my experience, if the C and M are not balanced up front grays will have a
cast. This is not only the density but the curve shape as well. I default to
2 for the nCurves.
If the initial ink restriction choices are not correct, then excessive ink
limits have to be imposed, causing clipping and posterization. It just seems
as though the icc has to 'work too hard' to try and compensate and gives
unpredictable results.
On the EcoUltra ink set we typically set
M very high, sometimes max, but usually in the 80-100% range.
We balance C so that after linearization the C and M curves overlap to look
like one curve, so C typically in the 40-80% range.
K we run just a bit higher than the C/M curves, usually near C in the 50-90%
range.
Y we tend to run fairly low in the 45-70% range-adding more yellow does not
significantly increase Y density but can add a lot of solvent leading to
banding/bleeding issues.
The key to solvent printing (even Eco solvent) is the evaporation of
solvent. The more ink you put down, the more solvent you have to evaporate.
The more solvent you put down the more dot gain comes into play producing
banding/bleeding (obviously media dependant).
The balance is between quality and gamut, this is the 'art' aspect of
profiling for outdoor media. Variations in temperature, humidity and media
all come into play. You can make a very 'narrow' profile with a larger gamut
that may work the current environment with the current lot of media, but may
not work well as the environment changes or with changes in the media."
I believe that some measurable and repeatable form of creating ink
restrictions would go a long way to solving inkjet printer consistency
problems.
Mark Rice
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