[argyllcms] Re: Calibrating problems in darks areas

  • From: Frédéric Mantegazza <frederic.mantegazza@xxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 29 Dec 2007 21:34:46 +0100

On samedi 29 décembre 2007, Klaus Karcher wrote:

> I hope my (rhetorical) question hit its target: it's useless to call the
> color cast of a emissive source without referring to a reference white.
>
> D65 for example is more yellowish than the native white point of a CRT
> (approx. 9300 K), but more bluish than D50, the standard light source in
> the graphic industry. When you switch between different monitor white
> points in a darkened room, you will notice a strong color cast, but
> after a few minutes your eye is completely adapted and your brain
> accepts the new setting as white. When you switch back to the old
> setting, you will notice a color cast in the opposite direction.
>
> D65 is the standard white point for home- office- web- and
> video-applications, D50 is the standard white point for soft proofing
> (when you have to compare images on the display with prints or proofs in
> a D50 viewing booth). Both are close to "average" natural daylight.
>
> Generally speaking it's important that the color and luminance of the
> monitor goes with to the room illumination when you want to assess color
> reliable and without fatigue.
>
> It's hard to attain this goal with a CRT in an office- or
> prepress-environment: As mentioned its native white point is close to
> 9300 K and you have to reduce the blue and green gain to hit the target
> color temperature. At the same time the luminance decreases and often
> you end up with a luminance below 80 cd/m2 at D50 -- definitely not
> enough for softproofing purposes.
>
> On the other hand, apparently some LCD vendors wear "brigther is better"
> on their sleeves: there are latterly some LCDs incapable to get much
> *below* 200 cd/m2 -- a great deal too much to feel comfortable in a dim
> environment.

Thanks for this explanation!

At 6500K, the contrast to maxium, I have a luminance up to 120 cd/m2. I 
always reduce it to 90-100.

As my wife has the same monitor, I'll make tests with it. It has no color 
cast, but the brightness is very low...

As you say, time to switch to a decent monitor ;o)

-- 
   Frédéric

   http://www.gbiloba.org


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