I'm having a discussion with somebody over on Graeme's list for ArgyllCMS. Chad's posted a GCATS file including spectral measurements he made of a ColorChecker SG using a ColorMunki. The alternating white patches around the perimeter all show significant signs of fluorescent brighteners present. They're flat at 86% reflective from 380nm - 420nm, after which reflectively rises very steeply to a peak of about 93% at around 460nm - 470nm, and then a gradual falloff to the red but with another smaller peak at 91% at 660nm. The spectrum isn't particularly smooth. The GCATS file has a calculated XYZ value of 89.467 91.727 91.969 and a Lab value of 96.709 1.8667 -13.059, decidedly very bluish...and I couldn't even find any common RGB spaces that can encode that without clipping the blue channel. I keep thinking that Chad must somehow have gotten saddled with a counterfeit product, as I simply can't imagine something like this coming out of X-Rite. But I've also never seen a ColorChecker SG in person...which is why I'm asking here. Is the ColorChecker SG really this heavily laced with FWA? If so, why on Earth...? If not, I'll tell Chad to get in touch with somebody at X-Rite on the assumption that something's worng with his chart (or ColorMunki or _something_). b&