Re: Possible ColorSync discontinuity bug introduced in OS 10.14.6 with display "r/g/bTRC" tags?
Re: Possible ColorSync discontinuity bug introduced in OS 10.14.6 with display "r/g/bTRC" tags?
- Subject: Re: Possible ColorSync discontinuity bug introduced in OS 10.14.6 with display "r/g/bTRC" tags?
- From: Wire Moore via colorsync-users <email@hidden>
- Date: Tue, 20 Aug 2019 15:42:01 -0700
Re "not a display profile," yes I know.
Maybe I misunderstand the original post?
The issue at hand as I took it is that when you config a MacOS display with
a minimal profile (e.g., working space) tonal rendering glitches in Preview
(and maybe elsewhere inc Photos, and I recall seeing a complaint about
Lightroom).
I am interested in this for its own sake, but also because if it's true, it
may be relevant to other known problems with certain display profiles.
Particularly per the stackexchange article reference I posted here last
week, about LUT display profiles made with DisplayCal.
And also per this thread on Luminous Landscape:
https://forum.luminous-landscape.com/index.php?topic=124542.0
What's confusing is that on the LL thread there's a post which seems to
dismiss the whole concern:
>>> "Has anyone tested this with another software product to confirm it's
an Apple bug?"
>>> "I did. There's nothing's wrong with Argyll XYZ LUT profile (High
Sierra 10.13.4)."
The dialog continues with another user's expression of doubt
>>> "I'm not at all confident we know yet where the problem is."
Someone else chimes in with "I don't use LUT profiles, so who cares."
At end the reference to Argyll XYZ LUT profiles working properly is
accepted as definitive and the convo peters out.
Well, over at the DisplayCal (GUI on ArgyllCMS) forums, it's considered to
be common knowledge by the developers that MacOS built-ins glitch XYZ LUT
display profiles, and have for ages. So much so, that DisplayCal UI directs
users to avoid XYZ LUT profiles in favor of matrix style. "XYZ LUT==AVOID
ON MACOS"
I can confirm that on latest MacOS 10.14.6 DIsplayCal XYZ LUT profiles are
still broken in Preview / Quicklook, and produce glitches similar to that
described in the old stackexchange post. (pls see my only other thread on
colorsync-user forum). And that Photoshop seems to have no problemo with
them—Apple is the only one getting this wrong is also conventional wisdom
at DisplayCal forums,
Moreover—to increase the intrigue—another user on DisplayCal forums, who is
using a plasma TV for a display via HDMI, is seeing the same glitch
symptoms with a DisplayCal matrix (***) profile as I see with an XYZ LUT
profile! A grey ramp basically rolls off to black up in the midtones, and
image tonality does weird things up high too.
So back here on this thread, with this discussion of classic working space
profiles producing glitches in MacOS Preview, it looks like maybe this will
all will come to a head and can get fixed?
That's where I'm coming from
On Tue, Aug 20, 2019 at 2:40 PM John Gnaegy via colorsync-users <
email@hidden> wrote:
> > When I set a basic RGB profile, like AdobeRGB, in Displays > Color,
>
> That’s not technically a display profile, it’s a “Space” profile. There’s
> also no ‘vcgt’ tag in it (though not all display profiles have those).
> Don’t know if that’s relevant to this behavior or not, but it’s something
> to consider.
>
>
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