RE: Finding CIELab Values from Target Chart TIF
RE: Finding CIELab Values from Target Chart TIF
- Subject: RE: Finding CIELab Values from Target Chart TIF
- From: Roger Breton <email@hidden>
- Date: Fri, 30 Apr 2010 07:25:27 -0400
Joseph,
> But it seems to me - evaluation or comparison of these 2 sets of Lab
values
> - pre-calibration and post-calibration - only shows the color difference
> between the 2 states - and not how close or far away it brings the device
> into conformance with - it's repeatable linearized state.
> Joseph
That's exactly what happens. And that's the great weakness of all those
systems, IMO, who only take a system from "no behaviour" to "some behavior",
but that behaviour isn't defined apriori, it is "adapted" or "derived" from
whatever conditions are found in the device. In a nutshell, today's
linearization will not equal tomorrow's linearization or linearization at
any future time. All these systems do is to distribute tone values between
two extremes according to a power law or some other math function, using max
channels saturation density and paper. The alternative, as some of the
better RIPs have it, like GMG's and ORIS's, is to bring back the printer in
an invariable colorimetric state after each "linearization". Now that's very
different from mere tone value "placement" which is the extent of
PhaserMatch and many dedicated, standalone packages like Onyx and a few
others. Nothing you can do about that. But it's better than nothing, right?
I feel your pain.
Best / Roger
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