Hello, A matrix profile is simply a linear transform from device RGB to linear XYZ. However, there also is a wtpt tag in the ICC profile from Argyll CMS. Where does that come from? Is the profile wtpt tag used to convert from profile white point to the white point of the PCS (a second computation step after applying the matrix perhaps)? I would really like some guidance on what to do about the white point for matrix profiles. Cheers, Stephen.