[argyllcms] Re: xicclu -g predictability issue

  • From: Elena [service address] <1007140@xxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 01 Feb 2011 14:58:49 +0100

Hello Gerhard

On 30-Jan-2011, Gerhard Fuernkranz wrote:
> While the "kz" locus is indeed smooth, the "kx" locus is discontinuous
> at two points. So any other black locus derived from the "kx" locus is
> supposed to be discontinuous too. But I'm curious where this "jump" is
> coming from. Is this just the result of inverting an almost flat, but
> still noisy/wavy region of the A2B table [i.e. a region which would be
> monotonically increasing or decreasing, if there weren't some ripples
> which break the monotonicity]?

I just made another test I had't made yet.
I computed a -ql profile to create a devicelink with, in order to
start from a very low resolution (5x5x5x5) A2B table. I keep on
using this way of using device links for testing, in order to reduce
conversions and interpolations to the bone. My intention was to check
whether starting from a so low resolution A2B table could have the effect
of filtering out any gamut irregularities possibly causing strong bifurcations
when inverting the table.
Unfortunately this is not the case.
Results still show the same abrupt discontinuities as when starting from high
resolution A2B tables.
Very strange...

(Attached slice plot of problematic area from red to black, -kz)
Using more K even worst, as always, of course.


Attachment: rtok_lqa2b_kz.png
Description: PNG image

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