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