Ben Goren wrote:
Is it safe to assume that the wtpt tag of an ICC profile is the actual paper color?
You should take it with a pinch of salt. As soon as FWAs come into play, the result depends strongly on the measurement device (UVcut or UV included?, UV amount of the light source?)
The paper industry uses UV calibrated instruments for precise (whiteness) measurements, but they are expensive and not suitable for profile measurements (it would take for days on end to measure hundreds or thousands of patches).
Graeme's method to estimate FWA amount is very elegant IMHO: he uses the curve shape as measure (UV absorption and blue remission of the FWAs cause a typical curve shape) -- but of course you need spectral data and it's still a estimation (albeit a much better estimation than tristimulus values).
On 2010 Feb 2, at 5:53 PM, Ben Goren wrote:X=0.899, Y=0.933, Z=0.751. According to Bruce Lindbloom's calculator, that's equivalent to D50 L=93.1, a=18.0, b=-5.6I might have some crow to eat. I just re-ran the numbers, and now I'm getting L=97.3, a=-0.112, b=1.61.
Ok, that's what I got too ... and it's much more realistic for the Museo MAX ;-)
If that's the case, then the Museo Max isn't at all pinkish, but instead quite neutral and bright. Right about now, I'd really appreciate somebody who actually knows something about all this to chime in....
Museo MAX might be a good white reference ... or baryta papers like Ilford Gold Fibre Silk (Lab 99,18 -0,17 -0,66 according to the whitepoint of a profile I have!)
I know both papers, but didn't test them with black light yet. Klaus
