Re: Pre-Linearization or Iterative Profiling (WAS Re: Printer profile mis-shape?)
Re: Pre-Linearization or Iterative Profiling (WAS Re: Printer profile mis-shape?)
- Subject: Re: Pre-Linearization or Iterative Profiling (WAS Re: Printer profile mis-shape?)
- From: Marc Levine <email@hidden>
- Date: Sun, 27 Aug 2006 10:16:38 -0400
- Thread-topic: Pre-Linearization or Iterative Profiling (WAS Re: Printer profile mis-shape?)
Darren, Scott, etc...,
Though I would chime in here with some additional info. On the topic of
MonacoPROFILER linearization, it is in fact a linearization. I think what is
missing in the text here is what a linearization really is.
Linear refers to a straight line. Linearization is the process of fitting
your device behavior to a straight line. That straight line can be based on
different metrics and will produce a different behaviors when different
metrics are used. For example, a printer linearized to density will look
different than a printer that is linearized to Chroma (a colorimetric
component).
Historically, linearization has been a practice that was adapted from the
conventional printing process, in which density and dot-gain have been the
long-standing measurements of value. Remember, there's no L-a-b knobs on a
press. The fact that densitometry has also been less expensive was an
additional compelling point driving calibration though density.
Cut to today. Spectros are cheap. Ink-jet printing is popular. Ink-jet inks
are funky (compared to process inks). Ink-jet inks are prone to hue shift as
the densities move higher, and the inks from different manufacturers look
and behave much differently. A spectro can capture this. Actually, a
colorimeter can capture this as well. A spectro, however, has the
distinction of being able to compute both density and color from a single
spectral measurement.
Anywho, back to the topic of linearization. When you have a spectro, you can
pick different metrics to linearize to: density, Lab, LCH - L* (lightness),
LCH - C* (saturation or chroma), Lab - a* (redness), Lab - b* (yellowness).
There's lots of ways to define a linear behavior using the information you
have and what metric you want to be linear to.
So my long-winded point here is that MP48 does linearize your device. It
uses Lab. When used in conjunction with a density-based RIP, it will change
how the printer prints, prior to printing the ICC target. These
changes/curves are built into the profile and used to "curve" the ICC target
numbers. The "curved" target numbers are then used to produce a profile
target for the optimized condition. Both the curves and the profile-tables
are then baked together inside the ICC profile.
X-Rite recommends not to use the MP lin in lieu of your standard
linearization process (which doesn't mean it doesn't work, it's just more
difficult to maintain as opposed to a RIP-based cal). You can do both
together - as Scott has recommended - but should probably target the
standard RIP-based cal for maintaining process consistency.
Hope this helps.
Marc
Marc Levine
Sales/Technical/Marketing....guy.
X-Rite Incorporated
email@hidden
www.xrite.com
> From: <email@hidden>
> Reply-To: <email@hidden>
> Date: Sat, 26 Aug 2006 12:01:59 -0700 (PDT)
> To: <email@hidden>
> Subject: Colorsync-users Digest, Vol 3, Issue 293
>
> Ah ha! This is where poor terminology can lead to confusion. The MP
> linearization isn't actually a linearization. This step is used for
> "device customized target generation" which makes a better profile
> with better gray balance.
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