1. A method for modifying a transformation T that transforms first colorants in a first device dependent colorant space into second colorants in a second device dependent colorant space, the method comprising the steps of: selecting at least one set of colorants in said first device dependent colorant space; transforming said set of colorants from said first device dependent colorant space to said second device dependent colorant space using said transformation T to obtain a set of transformed colorants; having at least one of the transformed set of colorants modified by a user; and automatically adjusting the transformation T so that a modified colorant set retains at least psychovisual or psychophysical quantity related to the set of transformed colorants.