NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/rec/video/13757

Internet Message Format | 1992-11-19 | 5.6 KB

Path: sparky!uunet!cis.ohio-state.edu!ucbvax!MCIMAIL.COM!0004861036
From: [e-mail] (James Millick)
Newsgroups: rec.video
Subject: Re XBR^2
Message-ID: <[e-mail]>
Date: 20 Nov 92 03:21:00 GMT
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Doug writes:
|>I have really fought with this problem on my Sony 46"
|>projection set. I could get the set calibrated for 6500K, but
|>the color on normal program material was terrible.  I almost
|>took the set back.  Then I found out 9300K works much MUCH
|>better, both on the projection set and on my small Sonys.
|>I really like the gray scales (parchment white and charcoal
|>grays) that you get with 6500K,

  I think you mean the color of white is what you like.

|>but program color (on both cable and laserdisk) looks good only
|>on some material.

  To properly track a gray scale means that the percentages of
Red, Green and Blue stay the same for every light output level,
from the darkest gray all the way to full white.

|>Yellows are too greenish in all material and while you can get
|>good flesh tones on some material, it looks too brownish and
|>harsh on most programs.

  This is not a function of the color temperature in and of
itself. I have yet to see a Sony KV or most PVMs that properly
decode NTSC composite to RGB. I suspect your problem is in the
decoding, it's not a color temperature problem. Your note implies
(forgive me if I'm putting words in your mouth) that sets
adjusted to 6500K will have color problems. This is not true.
YOUR particular Sony may have this problem, but it isn't the
6500K that is the cause. If that were true, the BVM-1910 which
comes preset at 6500K, will have color problems and it obviously
doesn't. If a set can't properly track a gray scale at 6500K,
then that's a design flaw, from a TPV point of view. Why the
insistence on 6500K? 1) Because that is what the NTSC is defined
as, and deviations from it will cause reductions in color
fidelity. 2)Film to tape transfers are conducted and monitored
*with* monitors that adhere to the NTSC standard. A director has
evaluated and adjusted his transfer to how it looks on a monitor
that meets the NTSC standard. A monitor that does not meet that
standard will present an image that is different from what the
director intended.

|>But with my sets calibrated to 9300K, I get very good grays and
|>absolutely gorgeous color on almost all program material.

  I would be interested to hear how you are calibrating your
color temperature. From what you say, it is obvious that the
decoding is tailored around 9300K, and that's why it looks better
there. There are certain cheats involved (not necessarily with
your set), some manufacturers slide the gray scale for a lower
color temperature in the lower light output levels (i.e., less %
of blue), then crank it up in the brighter parts (i.e., more % of
blue--some color temps may slide up to 12000K this way).

  The whole reason behind mfrs. using a high color temperature is
that they can get more light out of the set. The NTSC formula is
Y (luminance) = 0.30 red + 0.59 green + 0.11 blue. Y is luminance
or brightness information. The obvious way to get more brightness
out of this equation is to crank up the smallest component, the
blue, and that's exactly what most manufacturers have done. This
comes at the expense of color fidelity.

|>  Yellows are really yellow, grass is green, and flesh tones
|>are soft and natural more of the time.

  I don't know about your projector, I haven't evaluated a Sony
rear projector. I can say that all the KV series Sonys and all
but the PVM-1942/44 PVM series that I have seen DO have automatic
color correction (which it isn't) and auto tint. This means that
composite NTSC WILL NOT get properly decoded to RGB. Look at your
yellows again, is it really a lemony yellow, or is there orange
in there? There is orange in auto tint sets. Sony is an offender,
Zenith is worse. You also won't get a fire truck red out of it
either. If you know car colors, if you see a Porsche Guards Red,
it won't look like Guards Red, it will look like the VW-Audi Mars
Red, with orange in it.

  Lest you think I'm picking on Sony, I'm not. I think the
cylindrical Trinitron CRT is the best tube out there, in fact I'm
looking at my CPD-1304 as I type this. Sitting 15' away is my
PVM-2530, and every time yellow comes on, be it Bart Simpson or a
commercial, the stinking auto tint yellow pisses me off. If Sony
would make the auto tint and automatic color correction
switchable (I didn't say get rid of it, only GIVE US THE CHOICE)
on the 2530 and allow proper gray scaling at 6500K, it would be
one hell of a set. As it is, it is a well-built set that gives us
an *editorial*, not faithful view of the input.

|>Until the industry changes the standards for the NTSC
|>phosphors, I'll opt for 9300K over 6500K.

  This is not a function of the phosphors, it is your decoder. In
fact there is a better phosphor set than SMPTE C. "C" stands for
Conrac, a broadcast monitor manufacturer, who owns the patent to
the phosphor set. Why wasn't the better set used, you ask?
Because the owner (a Japanese manufacturer, I don't remember
which one) wasn't willing to share it at a reasonable cost so
everyone could standardize to it, where Conrac was. We SHOULD
have consumer sets that use SMPTE C phosphors, but we don't--yet.
Once again, the color troubles you are seeing are probably caused
by decoder tailoring to 9300K, and IS NOT caused by the phosphor
set or a color temperature of 6500K.

Jim Millick
Video Reviewer
The Perfect Vision