In print production, special transfer functions are applied to tune the conversion results. For example, the Adobe PostScript interpreter introduces the *undercolor-removal function* f_{UCR}(K) for reducing the CMY components and the *black-generation function* f_{BG}(K) for controlling the amount of black. Using these functions, the conversion from CMY to CMYK2 ( where ‘2’ stands for distinguishing from the above discussed form) is the following:

K = min(C, M, Y)

C’ = C - f_{UCR}(K)

M’ = M - f_{UCR}(K)

Y’ = Y - f_{UCR}(K)

K’ = f_{BG}(K)

The functions f_{UCR} and f_{BG} are usually nonlinear. Using the following formula, relatively close result can be produced to the Adobe PhotoShop’s result:

f_{UCR}(K) = s_{K}*K,

f_{BG}(K) = K_{max}*(K-K_{0})/(1-K_{0}) for K>=K_{0}, or =0 otherwise.

The formula’s parameters can be adjusted for improved result - the default settings:

s_{K} = 0.1 , K_{0} = 0.3 , K_{max} = 0.9.