What I just wrote is ambiguously phrased...
We attach a moniker to a profile for a standard, say sRGB. If it has the
name, it's for realz.
Elle Stone did something remarkable, she asked (I paraphrase) "How close
are 'sRGB' profiles to sRGB standard, and how well behaved are they?" The
answer turned out to be THE INDUSTRY DOESN'T KNOW - THERE IS NOT A
CONSENSUS. I'm sure any number of reps for various products are willing to
stand up to explain how their outfit has THE REAL SRGB.
OK, I especially like this idea that whatever the real sRGB is, it's
probably irrelevant because informed markets don't think like that any
more. Am I joking, or being rude, or I am just making a clear-sighted
survey of the industry?
How do I make this more concrete: For example, today, Apple platforms
cannot render cLUT display profiles correctly. This has been true for years
and years. MacOS accepts the profile, as it should — it's part of the
standard! — then they just render wrong. Whee! But because they are who
they are, we might just assume that the true standard is what Apple will
render correctly. Buyer beware I haven't tested Monterey I just wait for
news that it is fixed.
[I have just spent 3 days trying to understand what Photoshop does when I
ask it to make a B/W gradient and you might not be surprised to learn that
it doesn't make a perceptually uniform gradient, and if you want one it's
no at all obvious how to get one, and moreover, if I ask different parts of
my desktops to render a simple gradient, I get very different results based
on no obvious criteria that I can determine, subject to the whims of the
display profile. CMS seems to work and it seems to not work...
I'm giddy... Move along... Droids.., Not the ones I am looking for... /w
On Fri, Nov 5, 2021 at 5:36 PM Wire ~ <wire@xxxxxxxxxxxxxxxxx> wrote:
My thought was that what Yves is describing is the same issue that Elle
Stone described years ago:
You reply on certain "standard" profiles, but why do you think they they
are proper standards?
Maybe I don't grok the finer point Yves is making....
Carry on!
On Fri, Nov 5, 2021 at 5:16 PM Ben Goren <ben@xxxxxxxxxxxxxxxx> wrote:
Elle has lots of great stuff, though she (like many of us) hasn’t been
updating her site of late. So, in general, I’d recommend her site as a
great starting point with the caveat that things move fast in this field.
The way that caveat would play out here is that I don’t think anybody who
cares about color management these days is using sRGB as a working space,
though I’m sure basically everybody (knowingly or otherwise) renders to it
as part of a publish-to-the-Web workflow. At that point, the discrepancies
in sRGB profiles (which she documents perfectly) become moot … what matters
is the sRGB profile built into operating systems / Web browsers of the
people looking at (“consuming”) the works. I’d like to think that vendors
of OSes and browsers these days have settled on a not-miserable sRGB
profile; and, if not, I would assume that color profiling in general on
that particular platform is unreliable. (Of course, if whatever you’re
using to render to sRGB has a bad version of the profile, that’s also a
problem.)
Or: the problems with sRGB that she documents are real, but generally not
something worthy of individual attention any more. If it’s a problem for
you, you probably have bigger fish to fry first.
b&
On Nov 5, 2021, at 4:38 PM, Wire ~ <wire@xxxxxxxxxxxxxxxxx> wrote:
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
