[argyllcms] should I load matrix-shaper icc profile before profiling in several steps? & a few general questions

  • From: David Heinrich <dh003i@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 10 Dec 2009 09:37:57 -0500

I ran dispcal to generate a shaper-matrix profile of my CRT and did

sudo ./dispcal -v -d2 -yc -qh -b96 -gs -H -t 6500 -T 6500 -e4 -P0.5,0.5,3 -o

I got out the .cal and .icc files. Now, when moving on to "Profiling in
several steps". For best results, I presume I should use the shaper-matrix
.icc profile and .cal files I generated from dispcal when generating targets
and taking readings (is this correct?). What about loading or clearing the
.icc file from the LUT? Is the .icc file generated from the shaper-matrix
profile automatically loaded into the LUT before dispcal exits? If so,
should I clear it from the LUT using dispwin? If not, should I load it to
the LUT using dispwin?

Also, presuming I go through the section on profiling in several steps...I
presume I still always need to first do the "adjusting, calibrating, and
profiling in one step" part first, right? Because the "profiling in several
steps" doesn't deal with adjusting & calibrating the display part? But then
when I do back to re-do things in half a year or so, if I want to use the
previous profile & calibration to start out with, what do I use? Basically,
lets say that I go through doing everything in one step, then profiling in
several steps right now. In 6 months, what do I do when the CRT may have

Also, a question re LUT-based profiling vs. shaper-matrix profiles. The
documentation says:

"A shaper/matrix profile will work well on a well behaved display, that is
one that behaves in an additive color manner, will give very smooth looking
results, and needs fewer test points to create. A LUT based profile on the
other hand, will model any display behaviour more accurately, and can
accommodate gamut mapping and different intent tables. Often it can show
some unevenness and contouring in the results though."

My understanding is that Shaper-Matrix profiles sample various points,
several hundred, then use some kind of function-curve to interpolate between
them. While LUT-based profiles sample or can sample thousands of points and
the curves will run through each point. My question is, from one point to
the next, does the LUT-based profile simply do a linear interpolation? Or
does it do a kind of curved interpolation from point-to-point?

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  • » [argyllcms] should I load matrix-shaper icc profile before profiling in several steps? & a few general questions - David Heinrich