Color temparture and calibration w/ ColorVision SpyderPRO

Archived from groups: rec.photo.digital (More info?)

I've noticed that there are quite a few people in this forum who use
(and seem to be happy with) the ColorVision Spyder. I've got the pro
version, and I've got quite a few problems with it. Perhaps I don't
fully understand color calibration and color temperature.

I have a notebook computer with a flatpanel display. (Stop screaming,
I know I shouldn't be using it for color-critial work in the first
place. But in the field it's all I have and I might as well try to get
the best possible performance out of it.) The color temperature of
this display can NOT be preset. It seems to be set to a fixed 9300K
and color representation is far too cool. (I generally prefer to work
at 6500K color temperature.)

Now it is my understanding that a monitor presets its color
temperature (9300K, 6500K, 5500K, etc.) by varying the amounts of Red,
Green and Blue to arrive at the desired balance. In other words the
same thing a color calibration profile does.
So why can't my Spyder and the accompanying software (the most recent
OptiCal) achieve proper calibration for a 6500K target when the
monitor is preset to 9300K? Surely it's not the lack of tonal range in
the video card. Yet after the Spyder completes calibration my colors
are still way too blue. I've tried various calibration targets in the
software, but any deviation from 'native' makes it worse.

What am I missing here? I'd appreciate if someone can enlighten me.
Thanks!




Regards,
Frank

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A: People who can't be bothered to quote properly!
Q: What is the most annoying thing in E-mail?


============================================
Email: frankvw@euronet.nl
Homepage: http://www.vanwensveen.nl
============================================

Archived from groups: rec.photo.digital (More info?)

On Sun, 20 Feb 2005 03:13:26 -0800, "Moistened Bink" <me@privacy.net>
wrote:

> White point is not just a combination of RGB. There's also
> brightness and contrast levels that make the difference between
> accurate white, and something other than white (e.g. gray).
If you vary all RGB colors you will vary brightness, and contrast is
the possible amount of variation. Right? So I still don't understand
why this can't be achieved in a color profile...

> Color calibration devices assume the monitor has a preset for
> 6500K and is set properly. If your laptop is halfway decent
> it'll have a port for an external monitor. Attach one, set it to
> 6500K and see if you can get acceptable results.
I get acceptable results with my other monitors so I don't expect that
will be a problem. It's the notebook's flatpanel that I need to
calibrate, since I don't want to lug an extra monitor around for field
work...




Regards,
Frank

---

A: People who can't be bothered to quote properly!
Q: What is the most annoying thing in E-mail?


============================================
Email: frankvw@euronet.nl
Homepage: http://www.vanwensveen.nl
============================================

Archived from groups: rec.photo.digital (More info?)

"Frank van Wensveen" <frankvw@euronet.nl> wrote in message news37h11ljtqg6torrmrd49hruusqaggr27d@4ax.com...
> On Sun, 20 Feb 2005 03:13:26 -0800, "Moistened Bink" <me@privacy.net>
> wrote:
>
> > White point is not just a combination of RGB. There's also
> > brightness and contrast levels that make the difference between
> > accurate white, and something other than white (e.g. gray).
> If you vary all RGB colors you will vary brightness, and contrast is
> the possible amount of variation. Right?

No. The purpose of RGB gain is to adjust saturation and tone,
not brightness. You'll notice if you set RGB to 100%, there is
still the same (or nearly the same) range of possible white points
depending on brightness and contrast levels.