A method for creating a color conversion table for determining an ink volume discharged by a printer, the method comprising: a virtual chromatic value determination step of determining a plurality of virtual chromatic values (y) at a lattice point in a color conversion table in a virtual color space; and an ink volume determination step of determining a combination of the ink volumes at the lattice point in the color conversion table based on a predetermined transformation coefficient and the virtual chromatic value, wherein at least one of the virtual chromatic value determination step or the ink volume determination step is performed using a cubic spline function defined by the plurality of virtual chromatic values or the ink volume; and wherein at least one of the virtual chromatic value determination step or the ink volume determination step defines a first cubic spline function, the first cubic spline function having the virtual chromatic value or the ink volume as a dependent variable (y i-1, y i, y i+1) and a value of a lattice point in a device color system as an independent variable(x i-1,x i,x i+1) with respect to three consecutive lattice points to be processed, the three consecutive lattice points to be processed including an intermediate lattice point (i) with the virtual chromatic value or the ink volume to be determined and two end lattice points (i-1,i+1) with the virtual chromatic values or the ink volumes that are already determined sandwiching the intermediate lattice point, and determines the virtual chromatic value or the ink volume at the intermediate lattice point to minimize a sum of squares of second-order derivative parameters (y" i) of the first cubic spline function at the three lattice points to be processed. a virtual chromatic value determination step of determining a plurality of virtual chromatic values (y) at a lattice point in a color conversion table in a virtual color space; and an ink volume determination step of determining a combination of the ink volumes at the lattice point in the color conversion table based on a predetermined transformation coefficient and the virtual chromatic value, wherein at least one of the virtual chromatic value determination step or the ink volume determination step is performed using a cubic spline function defined by the plurality of virtual chromatic values or the ink volume; and wherein at least one of the virtual chromatic value determination step or the ink volume determination step defines a first cubic spline function, the first cubic spline function having the virtual chromatic value or the ink volume as a dependent variable (y i-1, y i, y i+1) and a value of a lattice point in a device color system as an independent variable(x i-1,x i,x i+1) with respect to three consecutive lattice points to be processed, the three consecutive lattice points to be processed including an intermediate lattice point (i) with the virtual chromatic value or the ink volume to be determined and two end lattice points (i-1,i+1) with the virtual chromatic values or the ink volumes that are already determined sandwiching the intermediate lattice point, and determines the virtual chromatic value or the ink volume at the intermediate lattice point to minimize a sum of squares of second-order derivative parameters (y" i) of the first cubic spline function at the three lattice points to be processed.