Patent ID: 8049939

Claim:
A method of generating transfer functions to be applied to input data of an image to be printed by a printing apparatus using a group of colorants, each colorant being assigned to the rendering of a distinct color channel, said method comprising the steps of: determining a maximum total area coverage; measuring the tonal response of each colorant; determining an individual maximum coverage value for each colorant by (a) establishing an individual coverage value for each colorant at one and same trial value of the optical density, (b) replacing the one trial value in the step (a) with another trial value and repeating the step (a) until a sum of the individual coverage values for each colorant at a current trial value of the optical density is substantially the same as the maximum total area coverage value, and (c) setting the individual coverage value for each colorant at the current trial value of the optical density as the individual maximum coverage value for each colorant such that the optical density at the individual maximum coverage value for each colorant is the same; and generating a transfer function for each color channel based on the set maximum individual area coverage for the assigned colorant.