During the process of creating a density adjustment table, when the average value avg for ink amounts of Ci(n), Mi(n), and Yi(n) is less than or equal to 2 at some density level indicated by positioning number n, a CPU sets a correction range of 1 to n, which includes the subject density level with positioning number n and gradation levels lower than the density level with positioning number n. The CPU 5 corrects the n-number of sets of ink amount data (Ci(n), Mi(n), Yi(n)) within the correction range of 1 to n, and converts each data set (Ci(n), Mi(n), Yi(n)) within the correction range into a corrected data set (Co(n), Mo(n), Yo(n)), wherein Co(n), Mo(n), and Yo(n) have the values equal to the average value avg of the original ink amounts Ci(n), Mi(n), and Yi(n).