Re: NEC PA271Q "Native" chromaticities
Re: NEC PA271Q "Native" chromaticities
- Subject: Re: NEC PA271Q "Native" chromaticities
- From: Wire ~ via colorsync-users <email@hidden>
- Date: Fri, 3 Jan 2020 10:04:02 -0800
Re calling out illuminant:
I'm not up to speed on why DIsplayCal calls out "illuminant relative", so I
included in case it affects the interpretation.
The numbers I supplied are stored in the profile made by DisplayCal and
accessed using the companion app ICC Profile Info.
I'm not clear about the science, but my thought is that because the whole
diagram is a model of perception, and there is visual adaptation, then a
CIE graph always has to be referred to some illuminant, e.g., the
standard illuminant? Honestly I am just BSing here, and would like to
understand this more. Continuing my BS guess is that the only way to
backtrack from xy coordinates to some spectral power distribution is under
the assumption of an illuminant? Given that display white point is
variable, then maybe this is just being super clear that it's referred to
the target of the profile. I should should shut up...
Re uniformity:
The unit certificate (Dell's cal report that comes in the box) claims Dell
measured < 2 dE across board, with a report focus on uniformity, saying the
report is based on a feature called "Display Uniformity Compensation" being
enabled. However some modes—at least Custom Color (native)—disable this
feature.
My report of a whitepint variance across the panel left/right (which while
unwanted seems typical of the IPS tech) was using the display in native
mode, so uniformity compensation was off. I assume the Adobe RGB mode
enables it, but I didn't think to check white uniformity when I ran the
Adobe RGB cal. I don't know how it works.
Re your previous messages with NEC / NTSC XY plots. I chose the UV plot for
better perceptual accommodation when comparing 2D gamut coverage. The
slight Green deviation you noted in a previous message will be more
accentuated by an XY plot, but this also inflates its significance in the
plot as compared to the other primaries. I understand what you were looking
for: the engineers had to make a tradeoff to get the panel to do both Adobe
and P3, so there's a tiny bit of missing coverage in one vs the other.
Irrelevant to user, I think.
Basically—if my measurements and report can be trusted—this display appears
to cover the popular use cases when combined with custom profiles in native
mode.
It has a great stand, including rotation. And does HDMI/HML and DisplayPort
with DDC/CI. And it has a high current USB3 hub!
Looking at the user guide, Dell sells a branded i1d2 and "PrecisionColor"
app that appears to know to interact with the display via DDC/CI so that SW
can select personalities. What would be cool is if you could load a custom
profile into the internal LUT. But I don't think it supports this.
In a nutshell, it does what's claimed, it looks gorgeous to me. And at $300
delivered, it seems a good buy. Very pleased.
On Fri, Jan 3, 2020 at 9:21 AM Roger Breton via colorsync-users <
email@hidden> wrote:
> I take it that 'Illuminant-relative' means the actual (raw) values returned
> by the instrument?
>
It's almost on the nose of the NEC PA271W chromaticities, practically the
> same 'gamut'.
> For a whole let less money. But what about the 'uniformity'? Can't say how
> comparable it is, for I don't have a PA271W but that's an important
> quality.
> / Roger
>
> -----Original Message-----
> From: colorsync-users
> <colorsync-users-bounces+graxx=email@hidden> On Behalf Of
> Wire ~ via colorsync-users
> Sent: January 3, 2020 12:12 PM
> To: email@hidden
> Subject: Re: NEC PA271Q "Native" chromaticities
>
> On Fri, Jan 3, 2020 at 7:54 AM <email@hidden> wrote:
>
> > Are you able to post the measured RGB chromaticities?
> > / Roger
>
> Dell UP2516D primaries as measured using DisplayCal / Monaco Optix DTP94
>
> I haven't sanity-checked these numbers, so if something looks weird please
> say so...
>
> Display in native mode:
> Chromaticity (illuminant-relative)
> Channel 1 (R) xy 0.6829 0.3123
> Channel 2 (G) xy 0.2256 0.7248
> Channel 3 (B) xy 0.1515 0.0486
>
> Display in Adobe RGB preset mode:
> Channel 1 (R) xy 0.6441 0.3301
> Channel 2 (G) xy 0.2278 0.7157
> Channel 3 (B) xy 0.1515 0.0562
>
> /wire
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