RE: Dry Time for UltraChrome inks/Calibration
RE: Dry Time for UltraChrome inks/Calibration
- Subject: RE: Dry Time for UltraChrome inks/Calibration
- From: "Darrian Young" <email@hidden>
- Date: Tue, 4 Feb 2003 19:04:56 +0100
Robin Myers wrote:
<By limiting the amount of ink delivered to the substrate, you are using
the straighter (notice I did not say 'straight') portion of the
increasing saturation vector before it "hooks" around. It is one of the
"tricks" you must use if using L*a*b* color lookup tables since the
regularly spaced sampling grid cannot handle non-monotonically
increasing saturation.
As for density, I almost never use density measurements. They are
representations of the color as viewed through specific filters. These
filters were designed for CMY printing inks only (and photographic dyes
for transmissive density) and are not universally applicable to other
colorants.>
Ah - now it is clear. Your last post surprised me a bit as it seemed that
you were against L*a*b* usage defaulting for density - I now understand,
however, that your affinity for density runs as deep as mine. I recommended
L*a*b* over density as a step forward, which I think it is), (apart from the
fact that we are somewhat limited to the tools the RIP manufacterers give
us - unless you make your own software) but if you have a better method then
great! Going back to my main complaint, many RIP manufacterers use density
which leaves the choice of using it as well, or as you mention, doing
"tricks" to try to get something better.
<Analyzing printing colorants and determining how to create the best
color reproductions is a complex task that cannot be relegated to one or
two simple tests. It must always be analyzed specific to the color
technology involved in the printer (or any device, for that matter).>
Of course - that being said, however, don't you agree that this should be
the responsibility of the RIP manufacturer - reducing the need to be a color
scientist to get good color out of the printer?
<All that being written, I prefer to analyze inks with xyY chromaticity
diagrams and tonal reproduction curves (TRC). The xyY space is not
perceptually uniform (nor does anyone expect it to be so), but for well
behaved printers the color mixing occurs on straight lines in a xy
diagram (the rate of change along the line is non-linear but the line is
straight). This makes visualization easier, without the problems from
the color space encoding that you get in L*a*b* space. Once the problem
is understood using xyY diagrams and TRCs, I calculate color mixing in
XYZ tristimulus space.>
If this gives much better results than with L*a*b* as you mention, would be
nice if you did some contract work for a number of developers I know of.
Regards.
Darrian Young
MGV
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