> they aren't illuminant independent, but they contain enough information, > in order that *both*, a) the "true" absolute XYZ colors (under the > actual viewing illuminant) Actual viewing illuminant? You mean "adapted" from their D50-based original values? > and b) an illuminant relative transformation > from the viewing illuminant to D50 (that's how ICC-absolute intent is > actually interpreted by the ICC!) Viewing illuminant? That's starting to sound chinese to me :(( > can be computed from the profile. OK. > Without 'chad' tag, this is not possible, Right. It's not possible to adapt the colorimetry out to anything else without this information, as far as I know. > except in the special case, > that the profile is made for a D50 viewing illuminant (in the latter > case (a) and (b) will give the same results). Then, all D50-based measurements of my spectro in reflectance mode are considered "made for a D50 viewing illuminant", right? This is so confusing. Why did they change the rules? Roger Breton | Laval, Canada | graxx@xxxxxxxxxxxx http://pages.infinit.net/graxx