This article may be old news on this forum — I didn't search the archives.
Will the Real sRGB Profile Please Stand Up?
https://ninedegreesbelow.com/photography/srgb-profile-comparison.html
It might have technical issues; I am not in a position to vouch for it. But
it's a wealth of consideration on the topic at hand, and the author is a
passionate advocate of Argyll and free software with a great willingness to
share experience. Good stuff.
I mention my reservations with great respect for the work at hand. My hedge
is that this author wrote a related article on the horrors of using sRGB to
correct camera white balance that irritated me so much I wrote a long
rebuttal with counter-examples as part of a dormant plan for a personal
website documenting some of my own explorations. However, the more I wrote,
the more I discovered how clueless I am on points that matter most to me —
while I shake my fists at the complexity and inscrutability of this stuff!
Nonetheless I find it all fascinating. The overarching subject of color
management is a marvel, and a triumph of science.
I should add that I have no axes to grind professionally; I am an amateur
and just follow this stuff for the enjoyment and erudition, and with
heartfelt gratitude to all who contribute.
/wire
P.S. Graeme recently published as note where he asked the forum about
dis-inclusion of specific vendor i1d3 instrument support, and I was very
heartened to see the question asked as a normal process of respect for the
community. Whether the decision would go one way or the other is not my
concern. What hits me is the give-and-take on a principle of mutual
interdependence and respect. This community represents my ideals of
political philosophy and develops such ideals into its practice. Fine
character. Considering the zombie status of the colorsync-users list, it's
completely astonishing to me that a small cadre of enthusiasts led by a
couple of wholly independent tool authors keeps a dream of understanding
alive when a trillion-dollar platform company that once led this domain
can't even be bothered to review its own massively popular codebase for
regressions, much less contribute anything at all to its birds of a
feather. ...OK, I enjoy harping... My point is words of appreciation to all
who participate, and to these leaders (authors) who freely share their good
works. Thx
On Fri, Nov 5, 2021 at 3:55 AM Yves Gauvreau <gauvreauyves@xxxxxxxxx> wrote:
Hi,
I came up with a situation, I'm using this generic command line here
"xicclu -ir -pl -s255 -v0 name_of_profile.profile_extension".
My goal was to verify if the profile converts neutral RGB values to
neutral Lab values.
So I extracted a few profiles that dcraw embeds in converted raw files.
Then I use the command line above and neither sRGB, Adobe RGB, ProPhoto
RGB or Aces convert neutral RGB values to neutral Lab values.
I was puzzled that all the profiles from dcraw where not neutral so out
of curiosity, I tried with transicc from LCMS2 using transicc -v -t1 -i
profile_to_test.icm -o *Lab2 < neutrals.txt, and I got similar results,
ie. not neutral. But I also noticed a very small difference.
Here ProPhoto.icm is from Argyll ref directory.
xicclu -ir -pl -s255 -v0 ProPhoto.icm < neutrals.txt
0.000000 0.000000 0.000000
60.351602 0.000000 0.000000
100.000000 0.000000 0.000000
transicc -v -t1 -iProPhoto.icm -o*lab2 < neutrals.txt
LittleCMS ColorSpace conversion calculator - 5.0 [LittleCMS 2.12]
Copyright (c) 1998-2020 Marti Maria Saguer. See COPYING file for details.
0.0000 0.0000 0.0000
60.3521 0.0003 -0.0003
100.0000 0.0005 -0.0004
Curious to now if any of you have an idea why?
Yves
