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: Mon, 28 Aug 2006 19:41:47 -0400
- Thread-topic: Pre-Linearization or Iterative Profiling (WAS Re: Printer profile mis-shape?)
Marco,
> The way I understand it (my apologies if my language turns out not to be
> completely appropriate), this "pre-linearization" (PL) of the target does
> nothing more than just change what color numbers are being sent to the
> printer when one prints the target.
[ML] Exactly correct. Which is exactly what the linearization curves in your
RIP do. Imagine the numbers for you digital CMYK patches on the other side
of a RIPs's calibration curves....different. With MonacoPROFILER, you are
getting a new target with values from the "other side if the curve". The
curve itself is kept in MonacoPROFILER and the resulting profile tabels are
welded together with the curves.
>
> Say that patch 3 in row one of your RGB target reads R 170, G 170, B 0
> before PL. After PL, the patch may R 194, G 165, B 0 instead. A majority of
> the other patches in the target will also change values, to some extent.
Everything will change, dependent on the curves.
>
> But this doesn't "linearize" your device in any way: it only sends numbers
> (this is the way I understand it) that will output colors on that device
> that, once measured, will be closer to the nodes in the profile's tables
> describing its output. The point is to facilitate the math inside the
> profile, so that the nodes and the interpolations are more precise and more
> reflective of the actual behavior of the device, producing results that are
> both smoother and more neutral.
Um...no, and yes. What you are doing is linearizing the behavior of the
device by a different metric that should affect a more uniform distribution
of color sampling - which will ultimately help the profile do it's math. It
is not because the linearization aligns the target path values to the final
grid values in the rendering tables, but to simply produce a better behavior
to sample. Again, you can think of the lin curves in Profiler (that you
can't see) as a supplementary calibration curve that is combined with the
standard lin curve to produce a different behavior. Because the curve is
kept in MP, you need to apply the curve values to the target file before in
is delivered to the RIP where it goes through the "second" lin curve".
>
> To recap, PL generates a new set of color numbers in lieu of the original
> set of color numbers in the target. This target is then printed on the
> device, and hopefully the measurements made from the modified target will
> make the profiling software work more efficiently to describe the behavior
> of the device.
Yes.
> But in no way this "linearizes" anything.
Well....yes it does. It affects a linear state on the printer to sample the
"original" target values that we save into an interim "curved" state for
delivery to the RIP. Putting it a different way, you could take the lin data
from MP, blend it together with the standard lin data, and effect the same
type of linear condition that MP targets - only 100% in-RIP. You might need
a copy of Excel and a fancy calculator, but you could do it. You could then
run the standard target (un-lin'd) and you should get the same results.
> I don't see how
> this "pre-linearized" set of target colors would interfere with the
> linearization from a RIP, though I would think it advisable to linearize the
> RIP first, *then* build the "pre-linearized" target from that RIP's
> internally linearized output.
It doesn't interfere and it is advisable to calibrate in the RIP first. You
are correct that the MP lin should be performed after the RIP lin. If you
get this, then you get the gist. The only remaining piece is accepting that
the MP lin is actually a linearization - a point of decision that is up to
you.
>
> Being that I'm neither a mathematician nor a scientist, I can't explain it
> better than that. And if I made any errors in my description, I would kindly
> ask to be corrected.
>
I think you did fine. The key point is that you can linearize to a given
metric, and then linearize again to a different metric. In both cases, the
printer behavior is changed. When using the MP lin, you effectively align
the printer behavior that is more linear through lab space. It's not to say
that the device was linear in the first place, just probably to a different
metric such as density. When the behavior in linearized against a Lab
metric, it typically has the effect of creating a more even distribution of
color sampling, using grids of color combinations, throughout the profile
space.
Hope this helps,
Marc
Marc Levine
Sales/Technical/Marketing....guy.
X-Rite Incorporated
email@hidden
www.xrite.com
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