Abstract: The sub-scan feed is carried out by a fixed amount of F dots. When is set equal to k dots (where k is an integer of not less than 3), a number of used nozzles N in the course of one main scan (where N is an integer of not less than 3) and parameters Na, Nb, Nb, m, and L satisfy Equations: (1)−(4), (1) N=Na+Nb, (2) Na=m×k±1, (3) Nb=Rd(L×Na÷k), (4) F=Na, where Na is the number of basic nozzels, Nb is the number of additional nozzels, m is an integer of not less than 1, L is an integer satisfying a relation of 1≦L<k, and an operator Rd( ) denotes an operation of rounding a decimal fraction in parentheses.