IMAGE FORMING APPARATUS AND IMAGE FORMING METHOD

PROBLEM TO BE SOLVED: To improve accuracy of interpolation calculation to read values of a small number of patch patterns so as to reduce an error in γ data.SOLUTION: The following nine points are interpolated with a cubic spline: read values of patch patterns on an intermediate transfer belt (pattern reading point 1, pattern reading point 2, pattern reading point 3, pattern reading point 4, and pattern reading point 5); a maximum pattern reading point on the intermediate transfer belt; a minimum pattern reading point on the intermediate transfer belt; and extrapolation points 1 and 2 (control points for adjusting an amplitude at end points (reading points 1 and 5) of read values of the patterns).