Re: NEC PA271Q "Native" chromaticities
Re: NEC PA271Q "Native" chromaticities
- Subject: Re: NEC PA271Q "Native" chromaticities
- From: Wire ~ via colorsync-users <email@hidden>
- Date: Tue, 3 Dec 2019 16:06:37 -0800
More rambling....
Wayne, thank you so much for the insights on television display
engineering. Wonderful!
Regarding SMPTE, I subsumed gamut into the color bars.
But you’re quite right:
//[NTSC 1953] was originally conceived by Norbert D. Larky and David D.
Holmes of RCA Laboratories and first published in RCA Licensee Bulletin
LB-819 on February 7, 1951//
https://en.wikipedia.org/wiki/SMPTE_color_bars
Reading on about this, you can gain a sense of televisions assumptions
about color gamut, like it was so well understood and deeply coded into the
signaling system it wasn’t even a topic of concern.
SMPTE color bars cont.:
//The graticule of a vectorscope is etched with boxes showing the
permissible regions where the traces from these seven bars are supposed to
fall if the signal is properly adjusted. Below the main set of seven bars
is a strip of blue, magenta, cyan, and white castellations. When a
television receiver is set to filter out all colors except for blue, these
castellations, combined with the main set of color bars, are used to
properly adjust the color controls; they appear as four solid blue bars,
with no visible distinction between the bars and the castellations, if the
color controls are properly adjusted. //
Anyone who has used the SMPTE pluge pattern with a blue filter for consumer
video display alignment has had an experience with how gamut was taken
completely for granted under television standards.
So do we assume oblivious determination to a standard as an explanation for
the absence of the concern of gamut? Probably not. Better to assume that
CIE science was studied and the designers felt a high degree of confidence
that their choice of primaries would be no impediment to posterity.
My guess was that as television evolved over decades, the industry
discovered that NTSC 1953 had more than enough and other factors led to
seeking a finer compromise, which eventually became 709.
And lo-and-behold Wayne explains the sort of factors that would’ve
influenced the compromise with the following great detail, and I quote:
//The compromise to Rec 709 is strictly because those were the primaries
that were available that made bright CRTs with nearly equal gun currents.
The unequal gun currents in early "NTSC" CRTs were a terrible headache in
terms of maintaining equal spot size and gray scale tracking between the
guns. One should also note that the psychophysical sensation of
"colorfulness" is affected greatly by display brightness, and the TV
companies and their customers recognized this, although they may not have
had the research to support it at the time. In any case, customers much
preferred brighter pictures, a difference they could see immediately and
continually, while they could not detect gamut limitations without seeing
the TV side by side with the program stage itself.//
Fantastico!
Regarding gamma and history, I re-read and relish Poytan’s “Rehabilitation
of Gamma”
https://poynton.ca/papers/IST_SPIE_9801/index.html
And I currently lament how BT.1886 is becoming commonly misunderstood as a
new reference for consumer video displays. That's not what it's for.
Poyton begged ITU to close a gap in spec history so that production houses
have a formal spec for how to handle legacy content.
As to consumer video, choose settings that look good in your viewing
conditions.
As to this—and possibly openly contradicting myself—I’ve also been
mystified at the continuation SMPTE testing artifacts in digital video
systems. What does PLUGE even mean in computer-based systems? When was the
last time you saw a SMPTE film leader on TV except to make a meta point
that you are “watching an old movie.” It’s like the concept of ‘overscan’,
an absurd artifact. How do you get rid of this stuff! On video forums you
will learn about a certain sort of video fidelity nerd who gets very
animated about the limits of their Blu-ray chroma decoding and whether it
should be done in the player or the set, and how using certain bug-a-boo
gadgets in their HDMI chain enhances the picture. Now, if you’re used to
RGB graphics you think ‘What are they talking about, what with their chroma
sampling test patterns?!’ In computer graphics, you just expect all the
bits you send to be rendered by the display with ever more perfect
precision. ‘Please put these perfectly yellow pixels exactly there so
subbpixel rendering can make text look smooth.’ Computer graphics nerds
spend their time lamenting stuck or dead individual pixels, which they
count. ‘Our dead pixel return policy is 5.’ And what do h265 engineers
think about YCbCr 4:2:0. ‘Good work kids, you've already compressed the
hell out of that picture! No more work to be done here. Move along!’
I’m joking. My point is that we’ve gotten to a place where an immense
amount of historical baggage is coded into these formats, and in many ways
we don’t need to think like that any more—which the flip-side of my point
about sRGB gamut. I wonder if UHD TV is hamstrung by history, which is why
consumer color is moving towards web-meets-movies.
As to SMPTE, what are they up to now?:
https://en.wikipedia.org/wiki/Academy_Color_Encoding_System
//The system defines its own color primaries that completely encompass the
visible spectral locus as defined by the CIE xyY specification. The white
point is approximate to the CIE D60 standard illuminant, and ACES compliant
files are encoded in 16-bit half-floats, thus allowing ACES OpenEXR files
to encode 30 stops of scene information.//
You may have enjoyed these capabilities in features like:
//The Lego Movie, The Lego Batman Movie, Guardians of the Galaxy Vol. 2,
King Arthur: Legend of the Sword, The Grand Tour, Café Society, Bad Santa
2, The Legend of Tarzan, Chef's Table, Chappie, The Wedding Ringer,
Baahubali: The Beginning and The Wave//
I’ve watched the Lego movie and Guardians of the Galaxy Vol. 2 on a
properly aligned home projector and can say without a doubt that I missed
nothing in these movies because of the measured slightly smaller than
Rec.709 (read as shamefully lacking) gamut capability of the Sony
VPL-HW45ES.
Meanwhile, anyone who has ever printed anything at all is like ‘So you’ll
really get a sense of how fantastic these colors can be when you view under
the right light source!’ ‘Please see our affiliates section for suppliers
of advanced color corrected viewing booths.’
I’ve read how-to articles by prepress pros explaining “observer metameric
failure” to other printing professionals in terms of ‘how to tell you
customer that he’s wrong while becaming his color guru’. I am not making
this up:
https://sdgmag.com/features/metameric-failure
At which point I take Andrew Rodney’s perspective to heart: You have to
train people to appreciate the value of wide-gamut printing because this is
something they won’t comprehend unless you explain it to them using
specialized tools and test files that exhibit what they’re missing, because
it’s something they didn’t even know existed.
Andrew, I truly enjoy the video explaining WCG printing, and it reminds me
of a way-back-in-the-day a Mad Magazine riff about the pointlessness of
advertising the merits of color-TV on TV: Because if you don’t have a color
TV you can’t see the advantages, and if you can see the advantages you
already have a color TV. So in the WCG printing tutorial video, I do think
I can see what I’m missing… And I’m seeing it in sRGB! A lot of the
fine-art printing sector feels like this to me.
My inquiry stands: What does WCG printing make possible that people really
want? What's a seminal printed product that shows off the new powers of the
medium?
Let’s keep in mind the origins of Giclée is Iris proofers. And a French
pejorative.
I totally dig that more color can be a great sensation, and that printers
can do color that you want soft-proof.
And I’m not arguing that sRGB should be a limit, only that it’s been an
excellent compromise, and I feel the topic of gamut has never been both as
well understood and misunderstood as it is now.
To appreciate the diversity of perspectives on this topic, consider the
following:
https://ninedegreesbelow.com/photography/articles.html#ICC-RGB-working-spaces
There are some ridiculous observations in the above articles. For example:
https://ninedegreesbelow.com/photography/white-balancing-camera-jpegs.html#introduction
I did the suggested experiment myself with the supplied photo using
Photoshop and sRGB, and in a few minutes had results (of this genuinely and
wonderfully awful photo) equal to the results of the tutorial. I love the
opinions and curiosity of the author and it’s all truly well-intentioned.
When you are willing to patch GIMP to get a linear space sRGB to work the
way you think it should, I salute you!
And you can see how peoples expectations of performance become captive to
their tools, which is maybe my plight WRT WCG and sRGB.
I don’t have WCG displays, but I’d like to use them just to experiment with
what they do.
What it will come down to is whomever changes a big share of the viewing
market. And if anyone is on track to do it, it’s Apple.
Anyways… ANYONE ON THIS LIST KNOW HOW TO ENGAGE APPLE ON COLORSYNC BUGS SO
WE CAN HELP THE DISPLAYCAL GUYS MAKE THEIR USER EXPERIENCE BETTER? Thank
you.
Roger, thank you for opening Pandora’s Box.
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