Abstract: The calculation unit (220) is arranged for calculating based on an input target color (T,TV) as output a number (n), larger than three, of quantized driving values ([R?]o, [G?]o, [B?]o, [C?]o) usable for driving an electronic multi-primary display unit (200) with the same number (n) of primaries to substantially reproduce the target color (T,TV), and comprises a determination unit (224), arranged to determine based upon the target color (T,TV) quantized initial values ([R?], [G?], [B?], [C?]) for each of the driving values, and an optimization unit (232) arranged to determine the driving values ([R?]o, [G?]o, [B?]o, [C?]o) selected from a set (CS) of candidate tuples of driving values, determined based on the initial values ([R?], [G?], [B?], [C?]), as a candidate which leads to reproduction (RP) of a color which is closest over all candidates in the set (CS) to the target color (T,TV) according to a predetermined error criterion (E(R,T)).