Cory Papenfuss wrote:
Yes... way better, and without the numerical weirdness of the
local convergence. I've now only got a couple of patches that have
perceivable dE in iccexamin, and they're probably due to a glare on my
test shot. No more low-luminance progressive errors. I'm a little
curious as to what the two new "knobs" to tweak the spline fit do.
I've so far left them at default.
The sliders contol the trade-off between fitting error and smoothness.
Moving them up, will increase smoothness, but also the fitting error.
The two sliders correspond to the -r<avgdev> and -rs<smooth> options of
the Argyll CMS' profile command (see
http://argyllcms.com/doc/profile.html), with the exception that lprof's
Avgdev = <avgdev> / 100.
Both sliders map to a single smoothness/error trade-off metric
internally, so they are basically redundant, but have a different scale.
I think that one of the sliders will be obsoleted eventually.
People usually tend to desire highly accurate profiles, and mostly
measure the accuracy simply by comparing the profile to the same data
set that was used to create the profile (that's alo what happens if you
open the profile checker window after creating the profile). This is IMO
mathematically not well-founded. First, even a perfect fit to the
measurements used to create the profile does not imply that the profile
would fit as well for a different data set. Second, measurements are
never error-free, but always (sometimes more, sometimes less) noisy. If
you create a profile from measurements which have a random error (noise)
of say 2dE average, and if the profile fits this data set with say 0.3
dE average, then it is IMO very likely, that the profile is not really
as accurate as it seems; it rather fits the noise in the data, instead
of describing the avarage behaviour of the device more accurately. Given
such noisy measurements, a smoother profile with a larger fitting error
may actually describe the average behaviour of the device more
accurately, than an supposedly accurate profile, with a low fitting error.
Regards,
Gerhard
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