First thanx for answering!!! :-) >As I understand it, you can't just stick
your 288 data points in the>profile's LUT - but you can certainly build a more
complete,>traditionally-sized LUT from those data points using interpolation
->again Argyll does this. How accurate the resulting profile will be>depends on
how well chosen those data points are, and how well-behaved>the device is. With
all the inbuilt colour-correction turned off, I've>found six-colour Epson
inkjets to be extremely good from that point of view. Could you explain it more
detaily? I'm very interested. >Is there somewhere in a publication or on some
web site the algorithm >documented on how to go about for creating a LUT based
ICC profile from patch >measurement data? That's exactly what I want to know
too! I spend at least 3 weeks for searching articles for building a 3D clut
with little success. All the articles I have found are methods about estimating
the whole gamut like e.g. neural networks with radio based functions, enhanced
neugebauer equations, geometric interpolations like splines, tetrahedrons,
statistical regressions models. For me is estimating the gamut the next step.
But before I just need to know how to create a feasible icc clut from the
measured points for minimum requirements. As far as I understand the 'real
professional' icc printer profiles with the big cluts includes just more points
than the measured points that are interpolated/estimated from the measured
points. So want to try the following:normally a printer RGB clut has the
1D-3D-1D structure. I just let the values two 1D-tables directly pass through
(1:1) without any distortion and just write the measured 288 points to the 3D
table. So is this a feasible profile? Maybe some could give some hints. :-)
jus PS. Sorry for double replys, I'm not familiar with this mailing list. :-)
> Date: Sun, 17 Feb 2008 14:35:20 +0100> From: [EMAIL PROTECTED]> To:
> lcms-user@lists.sourceforge.net> Subject: Re: [Lcms-user] build printer
> profile - LUT B2A> > Guy K. Kloss wrote:> > On Sun, 17 Feb 2008 12:03:06 pm
> Alastair M. Robinson wrote:> > > >> Unless you especially want to do the
> programming for this yourself, you> >> might find that ArgyllCMS is a better
> fit for your needs - it has a> >> complete workflow for profiling, and with a
> bit of spreadsheet work it's> >> easy enough to use an arbitrary set of data
> points.> >> > >> > On that matter ...> >> > Is there somewhere in a
> publication or on some web site the algorithm > > documented on how to go
> about for creating a LUT based ICC profile from patch > > measurement data?>
> > > > "The algoritm" does not exist. There are many ways to do it. Basically>
> you need to fit a mathematical model of the device behavior to the data>
> points in order to determine the model parameters, and then you can> evaluate
> this model at each CLUT grid point in order to fill the CLUT.> If you have no
> a priori knowledge that the device behavior can be> expected to follow a very
> particular mathematical model, then> non-parametric regression is basically
> the way to go. And there are also> many ways to do a non-parametric
> regression, e.g. multivariate> polynomials, multivariate splines, radial
> basis function networks,> neural networks, etc. Another exercise is building
> the> perceptual/saturation tables and the reverse (B2A) tables, since this>
> additionally involves gamut mapping and the inversion of the fitted> model.
> All in all this involves loads of mathematics, and additionally> some art for
> finding a pleasing gamut mapping...> > Regards,> Gerhard> > >
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