[opendtv] Re: Back from ***The Tech Retreat***
- From: Jeroen Stessen <jeroen.stessen@xxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Wed, 7 Feb 2007 12:56:25 +0100
Hello,
Bert:
> Excellent presentation, Jeroen. I found myself having to check back to
> the MacAdams ellipses quite often, to see whether the different gamuts
> in your many examples really mattered all that much. Most interesting.
Thank you. But please note that the slides marked with an "H" in the
bottom right corner were hidden, including the MacAdams slide. I did
not have the time to show them all in only 25 minutes. However, I
did keep them in the presentation file so that people may refer to
them for extra information. As you did.
Also note that this was a two-men show, Dr. Naoya Katoh of Sony and
I have presented the topic of Extended Color Gamut for Consumers
together. His presentation is behind this link:
http://data.memberclicks.com/site/hopa/2007_xvYCC_forHPA_FINAL.pdf
This gives you all the background behind the xvYCC standard.
There are many more presentations there, but unless you can guess
their names you're not allowed to download them. These are for
paying attendees to The Retreat only... I don't even know why I have
given you these two links... There is also Jim Burger's hilarious
but very informative annual presentation on "Washington Update".
Jim, if you read this: you are the best !
I'm telling you: you should have been there...
Bert:
> Looks like the biggest bang for the buck is to extend Rec.709 gamut
> toward the red, at the bottom, and toward the red and yellow at the
> bottom right, which seem like small differences in the gamut diagrams.
My perception agrees with your conclusion: it's the red and yellow
that touch you the most. My colleagues kept telling me that I should
have made my illustrations in u'v' space, but that suggests a perceptual
uniformity that is not true either. Better to stay in a space that most
people know is non-uniform. For doing business you should use a 3D space
anyway, so these were just my "color for dummies" illustrations. ;-)
> Not such a big deal to extend up in the greens, even though that seems
> like the biggest change with digital cinema. I'll bet it's the red and
> yellows improvements that people notice most in digital cinema.
Agreed. However... a wider green comes with a brighter red primary.
This is due to the white point calibration: you need more red to
compensate for the far away green. This is what caused my "overflow
problem" when converting down to rec.709 standard gamut. So with a
wider gamut you can render not only a redder red but also a brighter
red, to the point of exaggeration. The extra colors in the green corner
are not so useful, there are no typical surface colors there, but a
wider green can be indirectly a desirable thing, up to a certain point.
I think that the digital cinema reference "P3" primaries were well
chosen, and that we will enjoy them for many years to come.
Did I mention Charles Poynton's purple hair ?
Best,
-- Jeroen
+-------------------------------+------------------------------------------+
| From: Jeroen H. Stessen | E-mail: Jeroen.Stessen@xxxxxxxxxxx |
| Building: SFJ-5.22 Eindhoven | Deptmt.: Philips Applied Technologies |
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